the way i recieved it was that the technical aspects of jiu-jitsu can be seen from the bottom.
though for mma, top is definately the biggest want, definately better know how to fight off your back.
i've found it to be more true for me and guys my size when it comes to ground fighting. most peopel are larger than me and dont have much trouble putting me back over, so i've learned to kinda expand my options for jiu-jitsu from guard.
lol definately have to agree with Chronic_Jiujitsu, my stomach is the very last place i'd want to be anyday.