i had a colt that was high-flanked (cryptorchid) and my vet told me if he hadn't dropped by two years old he wouldn't drop. my vet says it's bad news to leave him like that and he needed to be gelded (was gonna do it anyways). i can't tell you the medical reasons why he said it should be done, he just said DON'T leave a colt like that.
i got lucky, during the gelding process, they didn't have to cut him open. after he was sedated, the vet tech squeezed him as hard as he could and it lowered the high testicle enough that the vet could get ahold of it, pull it down and snip-snip!! saved me about $200 according to the vet! that was good news, cause at the same time they were doing this, they were repairing an umbilical hernia. i've just started the little twerp under saddle, he'd better turn out nice for all the vet bills!!