They do.
At least normal up/down connections work, don't have any X stairways but i dont think they should be problematic.
What i noticed, though, is that the hauled cart was slow and only loaded with 3 rocks each trip.
guess without a track we don't get the Minecart physics
Well, most people use up/down stairs (the X stairways) as their "normal connections", and ramps only/usually only when dealing with Trade Depots, or cart tracks. Of course the ramps work, I was saying that they might not use up/down stairs. Sure you don't have the cart set to leave when 50% full? Or maybe it takes long enough to load up to 50% that the default 2-week timer for that is already full?
You can also avoid crashes by using non-dump stops. Just alter the friction so it slows down the cart without completely stopping it, then a roller will be able to turn it without crashing.
It's still probably easier just to carve a turn into the track and use walls (if it's going fast enough that you need walls to avoid a derail).
From what I've read so far in other threads, the !!science!! of frictions rollers is still pretty iffy. How much is enough? What about varrying mass of cargo? And what of the cart itself?
The testing I've done so far indicates that lowest rollers don't have any extra friction (beyond the track tile they're built on). A low track stop + the track it's on have a friction 5 times that of a normal track tile. Above that, it's a bit iffy still, but medium is about 50, high is at least 800, and I've yet to see a cart go through a highest friction track stop. For comparison, a dwarf pushes/1 tile of low rollers pushes with an energy of 200, 1 tile of lowest rollers at 50, medium at 450, high at 800, and for highest my best guess so far is 1250. Exact effects of longer or multiple rollers I haven't tested yet. I'm still halfway through testing ramps, but 1 ramp down gives something in the area of 500ish energy (depending on how fast it's going before ramping down, interestingly). For more info see
this thread.
Yes, without a track, you're limited to guiding, and when guiding, a minecart is almost just like a big wheelbarrow (except you need to define routes, and they're not attached to only work with a specific stockpile).