Well, I usually play Scout or Pyro in 6v6, and people freak out if you play Pyro on a map other than Badlands or Gravelpit. It's a pretty spammy map for scouts too. Hence, I usually get slaughtered.
Then again, I've still got a terrible habit of being too aggressive as a scout, so that could be my problem.
I don't do 6v6 as it's usually boring as all hell for me. Then again, I don't really care for "competitive" play in general. I play to have fun with friends, if none of them are on I will usually play something other than TF2.
But scout-rushing is so fun...I remember on Badlands my opponents team complained about how we repeatedly scout-rushed our way to victory.
Then their team sucked or had bad soldiers and demoman, or a lack of competent soldiers. A soldier with some practice at rocket jumping for speed should be able to get to the point before the scouts can cap it. I'll usually start rocket jumping to the spire after the slower classes arrive, and if there's a scout or soldier/demo with me we'll cap it right after our team has capped mid. I actually don't mind using the Pain Train on that map since it makes for quick spire caps.
If one of the spies on my friend list is playing I can generally rely on them to be waiting on the last point for a spy cap which usually works on the first round. Whether they prematurely build on the last point in subsequent rounds (plus the number of engineers that do so) and whether the respawn timer works in our favor will dictate whether a spy cap can be successful after that, but a spy and a scout working together can help get shit done.
