PVC Maximum Flow Rate?

[catnip]

I'm about to replace my pump and want to get the best match to my piping size. The suction side is 3 1.5" PVC pipes joined just before the pump inlet. The return side is 1 (one) 1.5" PVC pipe, so I believe I am constrained by the single 1.5" return line.

Research across the web yielded several flow recommendations for PVC pipe of 2" of less based primarily on water/pipe abrasion effects:
5 fps or 32 gpm (1.5") - Conservative flow limit
7 fps or 44 gpm (1.5") - Maximum flow limit
10 fps or 63 gpm (1.5") - Absolute maximum flow limit

My question: based on practical experience in pools what is the flow limit I should shoot for to balance performance with pipe life/reliability (don't want to have to break up the deck to replace a leaking pipe!!).

BTW, the pool size is about 18,000 gallons, so the I can get a full turnover in about 7 hours with 7 fpm/44 gpm. And the sand filter is rated at 60 gpm.