I second what choppers says. I have a brushless on the HBKII (never had the brushed) and I fly 1350 mAh power packs and get about 10-14 minutes of flying, but boy it is hot when done. Motor is very hot to the touch and battery is a bit more than warm.

Jeff - the HBKII is a great fly around (wreckless/fearless flying for me) but is no where near as "locked in" as the T-Rex. Each has its place in the flying arsenal though. Don't know which I would give up if I had to. Enjoy the DX7. A handful in the beginning, but once understood it will change flying for you. Just keep plugging along without getting in too much of a hurry.