gooo project tien! that's been around for how long now? lol
yeah personally i think if Tien isn't given as a buddy, which would be the best option, then I'd make Krillin regenerate stamina faster in his mystic state. afterall, going Mystic is much different than SSJ or any other trans state. note that Adult Gohan can't go SSJ when he goes Mystic. having a faster stamina regeneration rate would make it harder to pin him down, and other than Frieza blowing him up, he managed to never die, having been the weakest fighter in the series. just my thoughts on that.
that way you could get away with not giving him a ton of PL, which isn't realistic, but still giving him an advantage in other aspects.
and i agree on the speed thing. unless it's basic fly speed, it's really not so useful. and even then, krillin is clearly not the fastest nor strongest, but he certainly is the hardest to finish off (assuming everyone else isn't dieing around him)