Well, on the amateur side here-I know that officially nothing but approved shorts can be worn-but on the side of unsanctioned stuff...I use the MMA term loosely, too. Mainly a stand up striker, I have worn a kilt boxing with no adverse effects. My biggest annoyance with compression shorts combined with hard protection is the fact that I have a fairly muscular/moving midsection, and things wander about, even without the kilt belt factor.