Basic idea seems good in concept. Few things that spring to mind:
-make the base suit just powered enough it can sustain it's own weight. Unless the weight can really be kept low enough while still allowing for all the stuff you wanna do with it for it not to hamper regular people wearing it.
((I rather expect it would be doable. More importantly, the hardpoints can't be hardpoints if they aren't affixed to something hard - the exo-frame takes care of rigid and secure mounting. I expect it'd be no more encumbering than wearing a well-fitted set of medieval armor - even if the weight is there, it's spread out comfortably over the entire body, and does not limit movement.))
-making an Avatar sized mech sans synthflesh sounds doubtful to me in terms of practicality, but maybe pw will allow it with sufficiently advanced new tech and handwaving.
((Yeah, we've already determined that. However, I still hold by the idea that a much cheaper, mass-produced every-infantryman giant mech (hence the project name, ATX - Armored Trooper Experiment) will be beneficial on the battlefield. If nothing else, it will wipe the floor with enemy battlesuits. The ATX, and MACS in general, is not just for the Sword's limited use - I fully intend to make them available to the rest of ARM forces.))
-I'd focus on the person/Mk.III sized version for now, cause I don't thing the fully modular design would work as well once you get into battlesuit range. Imagine building a fully modular car, it'd be more expensive than a conventionally build counterpart, or have less quality.
((Most of a battlesuit's equipment is internal, and the different loadouts available serve the same purposes, but are not interchangeable. The purpose of a modular design is to mass-produce the basic model, and distribute the modules to be equipped according to circumstances. Saves on logistics - if X people need to fight in Y types of missions and bring battlesuits along, then they either need X*Y full suits that is each intended for the specific role, or just X modular suits, and X*Y much cheaper modules to equip.))
-A suit built like this will be more expensive than something made in a more focused manner. Again, flexibility and moddability come at a price, be it resources/money or quality/durability. But the lease system might help with that. But,
-I think we'll have to be careful with that lease thing, to ensure it doesn't get to complicated (and stuff will invariably get more complicated during field use and if enough time goes over it). And finding a good balance token-wise might also be non-trivial.
((What I got so far (it's not official, it was just PW's first suggestion) is that lease of an equipment piece costs half of its normal price - but it's limited to the loadout of your suit, just the MACS-specific gear. Repairs are standard cost, full replacement is full price. I don't know if changing the loadout will cost anything - my initial idea was that it shouldn't, since the whole premise of the system is that you're free to change your loadout whenever. But perhaps for balance purposes, some sort of exchange cost should be included. Perhaps a flat cost to respec - i.e. regardless of what gear you're returning, you're docked the same 1-2 token every time you do it (once per mission if you do it, for simplicity's sake), plus any repair costs. So that you don't pay more for returning several cheap modules versus one expensive one.
Thus, keeping track of it is pretty easy. You constantly owe half the price of the modules you're wearing, which you pay back if you lose them. Pay an extra token if you're changing gear, on top of repair cost for damage and the lease price difference of the modules. It's a more cost-efficient system overall, assuming one isn't always locked into the same role and circumstances - so useful for the alien can opener retrieval teams.))
Individual modules are meant to be installable and removable by the user, quickly and without hassle.
I doubt that just anyone would be able to switch out parts, seeing as how most people couldn't even replace a piece of hardware in their computer, even with all the help one can get online.
((I dunno, how many people do you know that don't know how to dress themselves? Putting on a Mk1, with the associated plumbing, would be a more complex task than installing something like a rocket pack - you literally pull it on like a rucksack, pulling on the straps till it clicks into the hardpoint, and the suit does the rest from there.))
I don't know if Miyamoto's/Aresteve's advanced exoskeletons can do it, or are basically cheaper/more powerful for the same price or maybe better protected/designed,
As soon as a science team is freed up I'm putting them on a dedicated myomer upgrade project
I asked for a very comprehensive library of different designs to be made, so whatever is needed should be obtainable from there. I'm not sure why you'd tie up a science crew to do basically the same thing again (saying "but mine uses myomers" doesn't really mean anything, unless you could explain why those should be better than whatever ARESTEVE came up with. Hell, he might even have something like it himself, you'd have to check honestly).
((Yeah, I expect PW will have questions anyway, so I'll clarify what I want done then. But basically, your research wanted to improve on existing synthetic muscle - same principle, but more efficient, capable of using more power. I want to check and see if we can't make an altogether different kind of myomer, than what UWM uses, and that we use by extension. We have the snowglobe data, and at least some examples of strange materials that we could research and use. It's not that the existing synth-muscles are bad - it's just that we could really use something much more powerful, that doesn't come with the baggage that synthflesh has, so that Avatar-class combat machines could be used by anyone, and without worrying about what will happen if someone manages to damage it in exactly the wrong way.))
and you can basically trade intact modules back and forth as you require.
In how much detail has this been worked out? Does a person has to pay some extra tokens for switching out modules if they've been used (similar to how armory stuff loses value even if it's been used, even if it isn't damaged)? I'd assume it'd be like that, otherwise it'd basically be completely free equipment changes.
I'm personally not sure if I'm a big fan of the lease system idea, because I suspect it'll just turn put to be equivalent to owning the suit, but at vastly lower prices because reasons.
((It wasn't worked out in that great detail just yet, but I outlined the preliminary idea above. Think it'll work?))