One of the builders I've been talking with is absolutely adamant that using 2" instead of 1 1/2" pipe is a horrible idea. He says that only commercial installations use 2" pipe. He warns that using it for my pool will cause the pressure at the returns to be too low. Also, none of the normal pool fittings will fit 2" pipe, so many things will have to be custom and my hydraulics will in all other ways be completely fubar'd. He also says that running pipe back to the pad for each connection is a bad idea. He warns that since they won't be able to use buried tees to make the return pipe lengths roughly equal, I'm in for pressure balance problems at the returns.
Even setting aside everything I've read here, none of the hydraulics advice he's giving makes sense. From the dim mists of time, my fluid dynamics lectures whisper to me that increasing pipe diameter should decrease flow velocity, reduce work done to overcome friction losses, and actually increase pressure at the returns a bit.
Is there something special about pool fittings that makes my book learnin' useless? Will using all 2" pipe really cause massive fitting incompatibilities and ruin my pools hydraulics? I'm pretty sure the answers are no and no, but I hate disagreeing with professionals outside my specialty.