Ah, alright that makes sense then.

But how is spychecking NOT a part of this? IF you kill the spy beforehand you never get put into that situation, but yes, i do see what you mean.(besides, i've never ever been saved, nor have i ever seen anyone save anyone by airblasting or FAN-ing a spy away, maybe because it's so rare?)
Well, in the end, not much we can do about it, but it does suck about not being able to do that(but as i stated, i have NEVER seen anyone airblast a spy away...), it seems to be one of those things about 0.5% of the players will actually care about in the end, kind of like the L4D boycott....

I mean VANILLA TF2 FTW!

From what I've heard in "Srs Play" TF2, no one plays pyro or spy. But the change isn't SO bad, we'll adapt

They do play Pyro and spy from time to time.

If I ever play TF2 in a serious game, I will play spy, and we will see what happens.

They use them sometimes but they aren't flexible enough to be a class used all the time.

You will get owned by a coordinated team. If you want to play competitively you need to be good as the scout, Demoman, soldier or Medic. The other classes you can become quite good at easily enough since the skills gained from those classes and playing transfer over. A team would hate you if you playd Spy constantly

Scout- capable of flat out assault against all classes and caps 2x faster making him viable for any circumstance.
Soldier- same as Scout except the capping.
Demoman- lethal in combat against all classes and can even take out Engineer structures if they are encountered.
Medic- always needed, enough said.

Heavy- too slow for assault, defense he is viable as he is powerful at close-pb combat and doesn't need to move to kill people on the points. Sometimes used but not often.
Engineer- sentrys and teleporters are his only viable reason to use him but his sentrys are too easy to destroy. Sometimes for defense only, not as often as Heavy.
Spy- can be lethal at people but his easy-to-kill and counter nature make him not as trustworthy as a good Soldier or Scout. Rarely used.
Pyro- too easily countered by the Scout, Soldier and Demoman to be used effectively. His flames are easy to counter by the Medic or health packs. Sometimes used, not as often as Engineer.
Sniper- capable in combat and competitive matches but not as much as the other 3. Used sometimes, more so than the Heavy. If you are really good as Sniper, you can always be Sniper in any circumstances such as Bloodsire.

Just to add to Hawkes summary.

Scout - Best at taking out any enemy stragglers and the best at taking out the enemy demoman and medic.
Soldier - There will always be 1 pocket soldier, this soldier will stay along side the medic at all times and is the medics primary defence. The other soldier will usually play roaming soldier and will usually leave the medic to move to a better position.
Demoman - Normally fighting alongside the scouts seeing as enemy scouts will be hunting him down. When defencesive positions are set up the demoman will usually be on one side with stickies while the "combo" (Soldiers and medic) are spamming the other side.

Heavy is usually used for last point defence. Pyro can also do this job quite well. Engineer is used from time to time but the engineers main job is to stop the enemy scouts.

Snipers main job is of course assassination of a medic from a distance to give the team an advantage. Spy will usually be used once in a map as a suprise attack and then wont be used again as the enemy team will be expecting it.

This is also a very good article to read on competitive TF2 http://www.gotfrag.com/tf2/story/43759/

i'm a bit late but meh.

just want to say that i personally welcome all the constant tinkering and think they should do it more often, it forces people to change playing style from time to time, stops people whoring the same strats over and over and opens new strategies or closes old ones. basically it keeps it fresh and fun. but at the very least it shows valve care about the game.

competitive spies - the disadvantages outnumber the advantages but they are not useless. i've seen a spy take out the entire opposing team by catching them off guard (in competitive games against very skilled opponents) they are also ideal for taking out snipers or engineers when they are actually used. But a rushing spy will be gunned down instantly and a slow/cautious spy's inactivity will leave your team down a player until they finally decide its safe to move in.

p.s. a scout is a good spy checker and i do it often. i always run through 'friendly' players when i leave spawn or return to rearm. often saves an engineer, sniper or medic.