I installed the update pcercuei, thanks for the pointer.
Thanks also for the tip qbertaddict!
I reckon I might have misdiagnosed the issue. Coincidentally the same emulators which won't work and use the Gmenu selector, are also the same ones which I didn't realise require a BIOS image. Hopefully with that in place, I'll be good to go.
So false alarm, but thanks for the advice though, both of you.
I'm liking the Gmenu rom selector, a really nice way of having a unified GUI on the Zero across the emulators, but with the modularity of being able to update/setup the apps individually. I never had this quite working on my old Wiz, but the Zero is already feeling tidier.
As far as Gmenu goes, I wish all apps allowed you to move them between sections and assign a custom icon. Is this supported on an app by app basis? Was going to get skinning...