My PB talked me out of a 2 speed as well. Now I am putting in one. Stick to your guns. I think PBs are used to doing what they do, one or two pumps, one or two filters, that's it. Much easier for them to order, warehouse, install and service.

Your PB will probably have to order or find the pump you want - that is more work! The is NO downside to having a 2 speed pump, except the extra 100 or so it will cost, even if you only wire it for single speed now, at least you have the option in the future. Most states are moving towards requiring 2 speed pumps (or variable speed pumps like an Ikeric), your PB might as well get used to it.