Yeah, autosampling can fill up space quickly and the MPCs currently have everything loaded into RAM. This is where streaming, if we get it, will help, but at the moment it’s the flipside of having a ton of sampling space (and having everything instantly accessible while you’re working). I haven’t pushed it far enough that saving has been a problem myself, but it sounds like a progressive save system would solve that, at least after the first commit.
The MPC has decent support for keygroups, but it’s not going to compete with a full-on PC in this respect, and I’d usually be looking for ways to optimise any KG program - fewer samples, fewer octaves, resampling, and so on. Faced with a fantastic piano KG that takes up 90% of the MPC’s resources, I think I’d be looking for another solution. Again, streaming could be a magic bullet here, time will tell. In the meantime, you often have to approach the MPC as a machine with a limited budget and work out how best to spend it. It’s a generous budget, but it will eventually run out if you don’t keep an eye on it.
It’s a macro synth at heart, so it does trade complexity for results. My recommendation with hype is to head to the end of the presets and play with the templates there - blank slates for the various oscillator types and combinations. It’s not dissimilar to the Model:Cycles or aspects of the Digitone in many ways - streamlined might be a kinder term than dumbed down, but it’s still possible to do a lot of sound design within its walled garden.
You should find this is a quick & accurate process once you’ve seen how its done - it’s probably in one of the videos below already, but there are plenty of examples if not. I’ll often let the sampler run as I play a variety of sounds in and then chop it later this way. You can also add slices while sampling, which may be a useful option for you to at least get an initial foothold.
As you say, it’s a complex device, because it does so much. Your video game analogy is a good one, though, and I think you’ll find it will apply to the MPC as you use it more. It’ll never be as muscle memory friendly as the Digitakt, but to achieve that you’d have to whittle down the MPC’s capabilities significantly. This is one reason by DT + MPC remains a viable setup.
Just keep at it! I bought a Force a while after my MPC One, and I found aspects of that move tricky because the MPC workflow had burned in quite successfully.