1) Not so sure about GPM or that HP ratings meaning much. This 1.5HP Pump is only pushing slightly more water than my 1PH unit. (little more water over the waterfall). I was afraid the 2HP would be too much for my Filter... but I suspect it would not. Guess the question might be what this pump cost in electricity to operate over the 1HP it's replacing?2) Got this for the 2 Speed option, during summer really need to almost run 24/7 in Florida for my salt water chlorine generator to keep up. But on the low setting this thing isn't doing much at all. (Water just trickles down the glass of the waterfall.) Will see what I can get by with between running on low vs high.3) Is extremally quite... old one might have been more quite when it was new, but this thing is a huge difference.4) No problem with it priming itself on first go (I did fill the basket with water and let it run back into the pool for a bit). Have and inground pool and this pump is about 30' away from it.5) Instruction are pretty useless.... one LINE IN is on the SWITCH and one LINE IN is one the main motor - both are marked (if you have perfect vision) You will need female spade connectors to make the electrical connection... glad I had some. Old wiring was #12 Solid, I replaced it with some #14 Stranded which made it much easier to work with.6) As someone else stated... it does run hot or at least the pump metal housing gets pretty hot. So I'm glad I paid for the extra warranty.7) In the end a one for one replacement of my existing "quality" pool pump that lasted six years... would have costed about $900. I got this for $173, plus 5% back from using my Amazon Card. I view it as a disposable pump - will likly find out how these Asurion coverage plans work.