How "defacto" is having a hot air gun?
I know it will make my heatshrink tidier as I currently use a lighter, which often leaves black residue and it's too easy to set fire to the heavier/large stuff
I assume the $10 / £5 China guns are likely deadly or useless, but the $40-50 / £30 dollar range with temp control and various nozzles are they worth it? I don't want to spend hundreds of $!
Hot air is mostly for rework and disassembly as taking off an SMD chip without it is almost impossible without destroying either the chip or the board (or both). Passives can be sometimes removed with an iron (make a blob of solder and/or heat both sides with the side of the tip) but larger components with many leads are difficult, even if you use some special solder (like Quick Chip). Solder sucker and wick are almost useless for reworking SMD components.
I have the cheap Atten 858d that Dave has reviewed here:
It wouldn't do for reworking huge BGAs but for desoldering smaller chips, reflowing poor joints or crooked components and heatshrink it is perfect. And if it dies I will just get a new one because it was so cheap.
I had one of those Ayoue combo-stations with soldering iron and hot air in one before but I didn't like that - the thick hose from the pump was constantly getting in the way on the bench even though it is a tool that isn't used that often. The Atten doesn't have a hose but only a thin cable to the handle. Both the heater and a fan are in the handle, there is no pump there, so it is easy to put away when not needed, taking up almost no space.
However, if you decide to buy one of the Attens, verify the wiring before turning it on - there are many clones and copies around and some are dangerously miswired, with the metal case not being earthed and/or the metal nozzle being live.