Sadly true, as MG has such a good interface and file handling. Wish there was an easy way for people to support it with new modules based on the best emulators. Especially gutted as I supported it from the very earliest days when it was pocketGB, buying the modules for GBC and GG/MS.
Anyhow, there are so many variants of pocketsnes it will make your eyes water, but it may be worth looking at Masterall's version as I believe it is quite fast on smartphones and handles QVGA. It is very fast on my Loox 720, but only occupies 1/4 of the screen, even using Picard's GAPI tweak. Masterall has also done a new version of Picodrive for MD emulation (
http://www.modaco.com/index.php?showtopic=237281&st=0) which again is very fast but doesn't fill a VGA screen. I use mobiledrive for MD.
I think GG/MS are handled fine in Morphgear, as are GB/GBC.
For NES and GBA I would also back up Menneisyys' recommendations