Another small question, bit late as I have bought two pumps, I appreciate you can't run these pumps dry and in a perfect world you wouldn't, but are you likely to do much damage if they run dry for a second or two as gravity primes them.
My pumps are mounted below the tuns and the input pipes are <1.0m long. I suspect these pipes won't fill with the pump off unless I fit a bleed valve but will gravity prime within seconds once the pump is switched on. I am part way through my build so they are not plumbed in yet. I could fit bleed valves but they would be a pain.