It's more oppressing to force someone to play a class than to deny him one. RAGE is also significantly different.
Also note how we started chopping at TF2 and now we discover it's not very nice or we're not very good at it... balance is disturbed.
I agree with ignoring the class limit immunity althogether on maps with engineer limits; either be it NO ENGIES or FREE ENGIES.
I originally thought that class limit immunity would mean that you get a slot for that class, not kick one person already playing it.
I now feel guilty to do it ... it's kind of like legal griefing.
Regarding medic enforcing I think people are RAGEd when others interfere with their freedoms. Rules doesn't allow you to do something but enforcement is more similar to... rape. People will either quit or grief (willingly not doing the medic job ).
I like that
annarack is very evil

in suggesting an oft occuring thing in humanity: sacrifice one (or more) for the good of the many (or many more). Equality and free will thrown out the window.
The only people complaining imho are those who play to win and their drive goes higher and higher hurting the diversity of the server (n00bs, fun-players, meleers, and the general freedom of all) because they try to drag them all to a new level, a more competitive playfield.
SpA needs to do some soul-searching and decide how competitive their servers need to be. A prime solution for the SRS BUSINESS players out there is to go join the no-crits server.

Almost always empty anyway and if you want to be serious you can't get more than that. If it's too ... forceful

then make at least 1 or 2 servers labeled as FUN: where people are losers

and fine with it. Becoming too enRAGEd? You go chill on the no-crits (or the SRS labeled) servers, then rejoin or stay there.
Here's another solution(-ish): Give more SpA points to someone who is playing Medic.