Hmmm, so you, like me, see the value of a fast booting OS. The consensus of opinion by the intelligentsia here is that a fast boot is unnecessary, as you can juts leave your PC in standby indefinately, never ever turning it off. Despite this its odd how often someone comes along and thinks a fast boot is A Good Thing.
Standby is fine, personally I prefer hibernate (zero power state).
And there are any number of cut down linux systems that boot extremely fast if that's what gets you going. Personally I prefer a more rounded system such as Elive.
And yes, a fast boot
is unnecessary when you have options such as suspend and hibernate at your disposal. Why should I waste my time booting up from cold when I can come out of hibernation and have the added bonus of all my applications being just where I left them?
Back on topic which you choose will ultimately depend on if you have Amithlon-compatible HW and what SW you want to run. Amithlon runs 68k apps that are RTG only-so no games or demos, at an insane speed.
AROS runs 68 k software under emulation, and a limited range of x86 software.
Games that support re-targeting should work just fine, how many of those there are however is an interesting question.
Tbh I think XP having had BartPE run over it would be fine - the end result would be an extremely cut down windows system that would still allow the use of WinUAE. Or, if you absolutely must have something other then windows, a cut down linux operating as a launch platform for UAE would do much the same.