re: porting already existing emus
There's a little truth to that - but that's mostly not the case.
Stella (Atari 2600), Z26 (Atari 2600), Gnuboy (GB/GBC) , SMSPlus (GG/SMS), HUGO (TG16/PCE), NeoPop (NGPC), DGen (Sega Genesis), Bochs (X86), FMSXBox (MSX), Bliss (Intellivision), WinSTon (Atari ST), StepmaniX (Stepmania), PCSXBox (PSX) were all first in their respective categories.
The first version of X-NES came before the first version of FCEUltra. V1 of both of them were about a year ago. X-Nes was not very compatible, however, which is why I ported FCEUltra.
Hikaru did the first port of Gens, but there were many reports of sound issues and certain CD games would not play - so I ported Gens (GensXPort) to clear up these issues. Then came Xenesis. Now there's NeoGenesis which is really just GensXPort with a new name and the new UI that I'm putting on all of my previous work.
Similar situation with XBoyAdvance. There were already 3 diff. GBA emulators, but it seemed like every other day I would hear something about "none of the GBA emus do this or that". So I decided to do a port VBA also. Mine is the only one to play Tactics Ogre and Wario Ware's reflect game (among other things.)
Generally, my rule of thumb is to *not* port something that has already been done unless the only existing ports are lacking in some regard *and* development on them seems to have stopped.
So in a nutshell - no - I am not just doing what's already been done. Most of my work represents the origins of those various systems being emulated on the XBox.