I know this answer is basically useless because you already decided but i still post it for the sake of information.
Everything is guaranteed to work fine because the 3ds has a complete set of DS hardware inside. You can even play Japanese, US or EU games on any 3ds because only 3ds games are region locked (which is very dumb)
Like the Wii had all the Gamecube hardware (thats why you can't access USB ports in Gamecube mode or save games on SD cards/internal flash memory etc) and the WiiU will have complete Wii hardware (thats why WiiU can't play Wii games in 1080p the hollywood and broadway chips are to slow for this)
As long as you don't try to play games like some GuitarHero games that need the GBA-Slot of the DS/DSLite for the guitar grip you will be fine 100%.
The 3ds even boots into DS Mode complete with DS firmware and operating system etc.
P.S. off topic
Go buy the humble indie bundle V !
