Great work on this first release Squidge!
So far from the mame 116 romset, I've tested the following at 240mhz:
agallet - returns to gmenu
area88 - working, sound a little choppy
batrider - working, though sound is choppy
batsugun - no sound, runs smoothly though
bbakraid - returns to gmenu
cotton - returns to gmenu
daimakai - working (also ghouls rom works)
ddonpach - returns to gmenu
dfevron - returns me to gmenu
dimahoo - hangs on 'open zip'
dogyuun - loads to black screen
donpachi - working, choppy sound
esprade - returns me to gmenu
forgottn - working, though there is no way to rotate
gforce2 - returns to gmenu
gigawing - hangs on 'open zip'
gloc - returns to gmenu
mahoudai - working, sound a little choppy
mercs - working, sound a little choppy
outzone (set1) - not working
outzonea (set2) - working
quartet - returns to gmenu
rchase - returns to gmenu
samuraia - returns to gmenu
sdi - returns to gmenu
sonicbom - returns to gmenu
truxton2 - working
varth - working, sound a little choppy
vfive - working, no sound
I'll throw some more on there soon, though my cradle just arrived B)