Dude,
I have two rent houses and they both have 1.5" plumbing and a 3HP IntelliFlo VS pump and they work just fine. One was installed 10 years ago and one about 7 years ago.. They have been running 24/7 since they were installed.
The advantage of a large VS pump is that you can run it slow and move more water.
In my case, both pools have EasyTouch Automation systems, so it had to be the IntelliFlo..
The only downside to having a large pump is the price..
I see you have a DIY controller.. Do you intend to use it to control the speed of the pump? If so, I doubt you will be able to use the RS-485 that the IntelliFlo uses, but both pumps have the ability to accept discrete inputs for speed changes.. The SuperFlo VS requires a special cable, and the IntelliFlo requires an IntelliComm kit.. which translates discrete inputs into RS-485 commands
Thanks,-
Jim R.