Rating on the 858D says 700W. I can't say I've ever done anything particularly challenging with it, but it has never let me down and I have never had to screw with the temp setting or airflow to try to get it to chooch mo better.
The 858D has a very small footprint. It has the heater in the handpiece, so the cord is very light and flexible. So if it does meet your needs, you have a nice compact and reliable unit. I have a big diaphragm pump hot air unit, and it's been in storage since I got the 858D. If it doesn't work, you are only out $30.00 and you can buy a larger bulkier and more expensive unit with more more output. I can't imagine the Quik does too much more, though. A hot air gun has higher output, too, 1200W vs Quik 1000W. But at some point you need a preheater. You can't input that much heat onto a <5 square inch area on the top of the board, only, because you'll burn the board. My experience with a 1200W heatgun is that this is way more power than useable in any conventional way, even without a reducer. So more not necessarily better, unless you wanted to rig your hot air machine to be a preheater with a big ole diffuser on it. The main difference is that a higher rated heat gun might warm up a little faster from cold off the cradle. From a cold start, I wait about 5-10 seconds before using the 858D. It takes longer than that for the display to hit the set temp, but the parts (that I do) will reflow before that, anyway.