Right now I'm trying to convice myself that a variable speed pump is the way to go. Install a flowmeter and set the pump to meet the flow requirements of filtration or the solar based on test and not "Wild Guess" estimate of piping / filtration / heat system in operation before being built.
cons:
Expensive
pros:
Potential to save on electricity ( I haven't calculated what it would take to break even on that )
Use only what we need to run the gear not use what the pump requires
Maintain optimal flow rate for each configuration
Can be adjusted as our needs change
Can self prime making it useable if we do get an IG
Keeps me from having to go through estimating the requirements of a system that doesn't yet exist and living with it later

Sounds like I'm taking myself into it.