With regards to the issue of dechlorination, I'm finally convinced that it's ok to dechlor the whole tank and then pipe in water from the tap. If discus keepers can do it, then so can I. Everything I've read suggests that dechlorinator works near-instantaneously.
Regarding the temperature difference, I just match the tap temperature as close as possible to the tank, and fill slowly. The fill rate is much slower than I could (or am willing to) replicate using buckets. I have a spraybar close to the top that makes a trickling sound when the water level is low, and when it rises high enough, the trickling stops and I know to start paying attention.
Stuff getting sucked up accidentally: put a fish net over the vac end.
The python has also enabled me to keep tanks larger than 10 gallons. After doing my first water change manually on my 37g, and not having heard of the python yet, I was regretting getting a tank that required so much work. I'm now happily maintaining a 55, and would like to upgrade to a 90.
The one thing that didn't occur to me until I got the python is that it takes just as much effort to do a 10% change as it does to do a 50%.. and the same is true for changing a 30g versus a 55 or larger. It takes longer, but I'm just sitting there doing puzzles or something.
-Raymond