[vvanders]

If you enjoy fetching your rocket from a tree you can go higher.

Back when I was involved with some of the higher power aspect of the hobby(J/K/L/M class) we'd go our to the desert where retrieval was a lot easier. Even out M class stuff rarely topped 1500ft.

Minimum diameter can go much, much higher but usually your flight waiver has a fixed ceiling that you don't want to exceed.

[johnjones4]

I'd like to eventually start working with those more high-powered motors, but for a first flight I wanted to keep things manageable.

... and I also had a 400 ft limit with my permit.

[vvanders]

Honestly a little surprised you need a permit for the standard engine power stuff. It's been ages since I've been involved with the hobby but we used to not need one until we stepped above E class.

Bigger stuff is fun but also hits the pocketbook a little bit more.

[johnjones4]

I'm in the DC area where anything that goes up in the air is taken very seriously.

[plugger]

High Power = H Impulse and above. Also, if your M class flights rarely went over 1500ft those rockets must have been HUGE. I did my L3 on a baby M (M2250 - 9.4% M) and went nearly 20k ft AGL and Mach 1.9.