Reading through this whole thread, this one "signature" of a poster came to mind, as it popped up whenever this person posted.
"In all the history of the world, a riot has NEVER broken out at a Sci-Fi convention."
And once sports entered the discussion, I recall all the anger and violence that actually is involved with both the players and fans of sports teams.
A Star Trek uniform might get you looks, but I highly doubt it would provoke someone enough to physically harm you. Especially as a man... I could see someone trying to come onto a female a little too strong, but that's a different scenario.
You're more likely to get into an altercation wearing a sports jersey. People can get really riled up. I recently moved to the LA area and I feel like a walking target every time I wear my orange Giants sweatshirt. But I still wear it because I'm a fan.
Honestly, I've only dressed up in Star Trek uniforms when going to conventions, the Hilton's Star Trek experience years ago in Vegas, for a movie premiere, Halloween, and a Star Trek museum. I've had fun every time and after a bit, stop caring about stares. I always have fun.
I say if you're comfortable, go for it. It's just clothing. All the negativity here and comments about people's appearance and state of mind are disappointing. Have fun with being a fan and enjoy something that you purchased that made you happy. That was the whole point of the purchase, and the OP was doubt that some outside source put into your head.