Problem with keeping that huge force of spitters on 3rd front is that it may hurt our chances to capture larger city on front 2 later....
1) Revise soldiers to better models > I don't think that this is practical
2) Improve workers to the point when they will be better than soldiers both in TC and combat ability > We invested a lot of actions in workers and it is logical to keep improving them further. Giving them weapons, reducing their cost, improving their carapaces are all viable options.
3) Improve ravanchers to the point when they'll stop being nat-effort and become frontline melee unit. > It is a long road but it may be an option
4) Design new melee unit > Totally acceptable course of action if we can be sure that new one will be significantly better than soldiers.
I still think that we have to find uses for timber.
I think that leaving the spitters is a very good idea. The spitters will naturally redistribute over time due to reinforcements and losses. Leaving the spitters on front 3 allows us to put more force on front 3 now while we are focusing there and naturally redistribute our forces to other fronts without spending a die on it. If we have a choice between 20/40/40% and redistribute spitters, or 25/40/(35%+legacy spitters) and both result in an equal distribution of force, then we should take the more balanced reinforcements and let legacy units make up the difference. Having one of our fronts perpetually at half-strength is just begging for a blitzkrieg. Actually, given that fortifications provide a fixed amount of T.C., it would actually be really sensible for them to do a 98/1/1 split to force us to focus on one front while we can only spare a handful of workers to futilely claw at 10-metre tall smooth stone walls while a few conscripted peasants stand on top hurling crude language at our stymied force...
1+2) Maybe hunters will suffice, but we really don't want to just throw away good units. There is way too much risk involved in overspecialisation and too much advantage from combined arms. I recall a convincing analysis from someone that a large number of resilient units would draw fire from a few highly lethal units. I think that it is very important that we have energy-efficient workers for civilian duties, turning our workers into unstoppable killing machines might leave our economy barren. That said, we can make different strains of workers, and they would be a decent base for sturdy infantry that soaks damage. Then again, so would soldiers. Making small soldiers, or incorporating soldier elements into worker designs might be a good plan? There is something to be said for having something really big and armoured, for the advantage of thick armour that doesn't show appreciable damage from single hits... but given how little focus big units get... until they design assassins for focusing down our few expensive damage-dealers...
Long story short, throwing away designs i not all good. It is easy to look at the fewer actions required to develop them and see it as all good, but it is fewer actions to counter them too...
3) I am strongly against this. Revanchers are siege. Siege is a wonderful place for national effort, I would say that being able to easily shift them around to fortifications is greater an advantage than being limited to one front and restricted to 5% is a disadvantage. Again, maybe we could split the streams, but we may as well just build something new.
4) I would probably hold off on this. Lets us work on some new biologies on our various existing units and then build a new unit when we have a nice accumulation of resources to draw upon in their design. But we should definitely be aiming for revolutionary shifts rather than progressive shifts. We need good new parts to produce a truly impressive new critter.
Using timber is good. I still want to try metabolising it though. I still like my idea of converting it into a rigid glue that can be used to rapidly fortify tunnels...