Ok apologies as this is a bit long, but here goes....
Pony 14hh, 8ys, teeth checked 3months ago, ridden by lots of riders aged 8ys to small adults.
Was ridden in a french link, cheek piece snaffle - was ok but not perfect, could hack with breaks, could jump with control 'ish' could do a prelim dressage test, was fine. Would pull children around a bit and would always manage to get tongue over the bit, had a flash noseband that helped a little.
End of last year/early this year I had to stop riding him (because i was pregnant), he became a bit of a nightmare, started tanking off on hacks, running out at jumps, getting REALLY stubborn in the school. Really got to the end of my teather with him and changed his bit - I don't have access to a bit bank and the only thing I had that fit him was a pelham - he improved over night, even better than he ever was in the snaffle.
So, my question, if he was your pony would you:
a) leave him in the pelham even though not all his riders have steady hands (children/novices a lot of the time)
b) try something else, and if so what? keeping in mind he now has a harder mouth than before (so can't go back to old bit) and still has the tongue-over-bit problem (even though less with the pelham as it's vulcanated so less space IYSWIM).
Schooling, IMO, is not going to really help as I can still ride him in a halter - just seems that he's a bit of a one-person-horse and would have most other people off if they even tried!