While I applaud the technical ability behind writing an emulator for the DS, I do not see myself using any of them. The same goes for backward compatibility. Native DS games are much better than any emulated or previous GBA games; plus the DS catalog is now big enough.
If I owned a PSP however, I would probably use them due to the poor choices of games on that platform.
Now, if there was a working N64 emulator on the DS, that would be another story...