Re: advantage to 2" plumbing on pad with 1-1/2 in. incoming
I did just that when I was planning to re-plumb my pad for a new pump and solar anyway.
Biggest reason was to reduce the headloss in all the fittings. Sure the lengths are short, but all the Tees and 90s add a lot of head loss and by increasing the size you can reduce this and increase your flow rate.
BTW, all Jandy valves are 1.5/2 or 2/2.5 or 2.5/3. What this means is a 1.5" pipe will slip into the valve, but a 2" pipe is the same size as the valve inlet and you connect them with a 2" coupler.
If you are doing the work anyway, then it is cheap to increase the size. But there may not really be a point in re-doing the plumbing ONLY for the reason of increasing the size.