c-4 power limit

so i was at the local chassis shop (sub-frames and roll cage getting installed ) and the guys that worked there basically told me that the c4 was junk for my application. they said there is no way it will last with my setup, mabey a pass or 2. they said go with a c6, then later changed there mind to a powerglide (chevy guys) does this sound right? i thought the c4 is one of the best there is??? my original plan was a hardened input shaft b&m or tci rebuild kit and a manual valve body,
also ~3200-3500 stall-- if it matters
please tell me that the c4 will be fine, i already have one and really dont want to have to buy another

thanks
travis