Quick questions, am I able to use my physical memory cards with this?
GCReEx format or DiscEx format, which one to use? any advantage, disadvantage?
The audio streaming is this just music but all other audio is working?
-Memory Cards work fine and all games are compatible but careful with JAP game because some may format your Memory Card!
-I recommend DiskEx format, some said GCReEx format is faster but I never saw any difference in performance myself, can't say it's not there but if it's there it might be small difference, however DiskEx format has better compatibility as all my games are DiskEx format and work perfectly fine, plus you can always just copy the DiskEx file and use it with Dolphin if you want, not sure if that works with GCReEx though!
-Audio streaming is only for few games, in my huge collection here are the games with audio issues:
*Crazy Taxi (No music but voices and SFX work fine)
*Super Monkey Ball (No music but voices and SFX work fine)
*Looney Tunes Back In Action (No music but voices and SFX work fine)
*Namco Museum (No music but voices and SFX work fine)
*Crash The Wrath of Cortex (No music and no voices but SFX work fine)
I will point out though that USB compatibility is still not as stable and has some issues with some brands that go to sleep mode, so if your games can fit an SD you might be better getting the SD version instead!
Edit: A couple of things I forgot, DM doesn't affect playing with original disks but you will no longer be able to play back ups with it, also some games that use two disks still have issues switching between the two but most of them seem to work fine!