It shouldn't crumble.The only thing ,and it may not matter,is that I rarely cut them exact.I've done it with my Nucynta 150 and sometimes I have one piece that's 60 mg and one that's 90 mg.
I've heard of a Pharmacy doing this,but not many times.I'm not sure exactly why but I'd rather have 60 15's than 30 30's.
My only suggestion might be to limit the number of times you
open the bottle.Maybe get a weeks worth out at a time so they're not exposed to air,light every day.But that may not really matter.
I'm sure you'll be a pill splitting machine in no time.