Theres a couple different dynos around here with two different types of ways to gather A/F ratio. One shop will install a wideband sensor in my car to use and the other uses a sniffer at the tip(s). Is there a benefit to either one over the other or is it just shop preference? I would figure a wideband O2 would function slightly better than a sniffer setup at the tip. I'm just curious.

I would go with the wideband just after the collector. it will be more accurate in relation to rpm and a/f.

Wide band, the best of the best could use a wide band for each bank.