You also have to consider, HDTV's also have video lag if you're gonna test lag. More recent ones cut down on this, but it's still there. But if everyone is susceptible to it, by both using the same TV and adapter, then it's still an even playing field, although a different experience to what you're used to.
I've played enough Guitar Hero at high level on multiple TV's (And consoles, Wii and PS2 being Standard Definition and 360/PS3 being High Def, they are COMPLETELY different, sometimes 50ms different depending on the TV, making the game unplayable if you aren't used to it) to know that TV's make a MASSIVE difference when it comes to video lag.
The same can be applied to Smash, which is why people tend to opt fot SD TV's when playing Melee, HD TV lag can completely through you off.
I know my TV has about 3-5ms of lag, so if you want to test it thoroughly, you'll either need a good HDTV, or a SDTV. But from testing multiple ones for a good amount of time I find the lag negliable. It's not noticable if it's there in all honesty.
And I'm glad to be helpful @
ShuckleBoard
. c: