What would be a good first high power two stage kit? I have found kits from Public Missiles -Quantum II, RRDS - Orion, and US Rockets makes a number of kits. Does anybody have experience with these kits or can recommend another one?
I think you've shown excellent taste doing your first post on two-stagers! They are a lot of fun.
I started with the Quantum Leap, so it's the only one on your list that I can comment on. It is the shape and size of a generic 3" two-stager, but the kit has many problems in my opinion. I would list the top ones as flimsy fins (the Q-leap is famous for this), a poor method of lighting the sustainer (the motor should be lit from above and not from the booster), and the CPR system is a dead-end fork in the road of rocketry (in my opinion, having been down that road).
I got the kit and then made many changes to it. Unfortunately, I didn't go far enough in beefing up the fins and I shredded it (if you've seen the US Bakula video, which is a Q-leap, that's what my rocket did, except it didn't survive). So I rebuilt what looked to be the Q-leap, because the general idea is fine, except with dozens more changes to the kit design:
https://www.dars.org/contact.html
I have flown it perhaps 20 times as high as 18K and I really enjoy this rocket. My suggestions to anyone starting two-stagers (who have sufficient experience with single stage designs) is to get the plans for these two stagers and study them, then ask a bunch of questions, then build what you want scratch. There's lots of info out there on the Q-leap to learn from.
Jim