From what I've read, I can't help but believe that supporting other BIOSes on a microSD card is nothing more than a gimmick at the moment. There hasn't been much effort in supporting anything else previously with MakeMHz... And if it does go ahead, I can't imagine it'll be a priority at all or that any competitive/preferable modern BIOSes or patches will even be supported anyway.
I've been interested in the native ATA TRIM support for SSDs as well, but it's not something that I've really seen discussed since its announcement... Sure, it's not actually all that big of a deal, but I'm keen to see it play out if it's actually a thing.
All of the kernel-level patching on-the-fly is the most attractive thing about it all to me at the moment, and also the integrated modern controller support that I haven't seen or heard anything about yet either...
There's a lot of promises and undelivered features, but also a lot of drama and refusals to support desired features that are provided elsewhere. I think I'll be on the fence about Project Stellar for a while, patiently seeing how it all plays out and what it has to offer in the long-run...
I think that a bit of competition for an internal HDMI output mod (not analogue-digital external converters) could be a good thing for the project overall - I recently saw some mention of PixelFX developing one?
In the meantime, an OpenXenium with freedom for my own choice of BIOSes/patches will be good enough for me, at least until something "Stellar" finally happens with this...