I actually feel that 5GB is the "sweet spot" - for me, anyway. Any less and choosing which songs to put on can be tricky, any more and you'll find yourself skipping tracks to find one that you feel like listening to. Whilst I have about 15Gb of tracks on my PC, I think I've finally got the right mix on my H10, coming to about 4Gb - and that's at 320kbps! So in conclusion, bigger isn't ALWAYS better
I've used the UMS/MTP swap trick, so my player is now in drag-and-drop mode permanently, although you do have to run a program called "EasyH10" to update the database everytime you make some changes.
I'm currently using some new Sennheiser CX300 ear-canal earphones, and get a great sound out of the H10, especially in SRS WOW mode.
So from me it's seven thumbs up (out of eight). I would have given the extra thumb if -
A) Database updated itself automatically after drag and drop.
B) Battery life could be slightly better - I get seven hours or so, but that is at 320kbps, SRS WOW on.
C) It doesn't show album art while a song is playing, a feature I would have loved.
Hope that helps