This pyro swapping thing was done a lot more in the past. You can find even old eXtv demos where med players would off to pyro. I do it sometimes and have had decent results with it - last ESEA season I had a short stint as the top pyro in esea lol.
I don't switch pyro for the outset of the hold - it's mainly only useful when you're at both uber and player disadvantage. Say you try to take second, fail to do so, and you lose a bunch of people, one of which isn't the med, and they for whatever reason still have uber. Thus, it's essentially a desperation move. If there's no hope that you'll be able to get your spawns before they push, and there's 0 chance you can get yourself an uber (sawing people who didn't notice you) you may as well.
Worst case scenario, you blow the enemy off of the point and delay the cap for several seconds (perhaps long enough for spawns), or, best cast scenario, you get SUPER lucky and somebody gets crazy stupid and shoots a projectile at you, and you get an immediate 4-6 k and make a frag video.
At least when I do it, I just hold down mouse 2 until I run out of ammo as soon as anybody is in air-blast range. Then hope for axe and flare cheese kills, then run back into spawn and get back on med ASAP, unless I die valiantly.
The switch mostly depends on what % I'm sitting at uber wise. If it's 50%+ I'm staying med because 2 swipes gets me an uber and I'll take that over hoping that the other team doesn't understand pyro play.
Another tricky thing you can do, if you're feeling like taking big risks, is if you know you're at an uber disadvantage that's so great that the other team will just have to push (example: you die, their med doesn't pop to take your second and lives). You can run kritz. You're not going to get uber during the push anyways, but you *may* get kritz if you dip, duck, dive, and dodge, and then you can hope you get really lucky with that x4 damage.
As for Enigma. UGC teams, historically, prior to their knowledge of the IRC will typically just play whichever teams they've previously played in the league - or they'll research other teams in the league since the profiles page links directly to steam profiles it's not hard to try and set stuff up. Eventually, most go to the IRC. In previous seasons we put a lot more emphasis on getting preseason stuff set up so teams would, perhaps, get to know each other, but now the IRC is pretty well known even in the lowest rungs of the ladder + I made a video on how to use it that I distribute lol. (I've been a UGC 6v6 admin for... this would be my third season coming up).