I'm getting some errors running Overdrive (the first one, not 2 since that's PAL-only) on the Nomad. I am using the NTSC-compatible ROM. There are a few parts that don't display properly (a few frames before the no Nintendo inside rotating thing are glitched and the whole greetings screen doesn't work). I actually didn't let it run beyond the broken greetings screen; I was just testing to see if anything would seriously break and I turned it off when I saw that that screen didn't work properly.
I've heard that sometimes it (Overdrive in general and that screen specifically) doesn't work on real hardware for some reason. Not sure if this is a Nomad problem or a MegaSD problem. Will test it on my Mega Sg and Japanese Mega Drive when I get home from work tonight to see what happens. I know that Overdrive used to run properly through the Mega Sg's SD card slot, but the new firmware broke some stuff, including an actual cart game that no longer works, but I have not tested any demos since the last (custom) firmware update.
Edit: I forgot to disable the auto-region fix thingy in the MegaSD and I wasn't paying attention to see if it tried to do any of the region fixing stuff. Will try it again on all systems with that option disabled.
Edit 2: Emulate seek time = on, graphics scaler = off