Yeah, but imagine your primered helmet. It's totally grey. You take your dremel to it and chop the T out and you're left with 2 dark green edges on the inside of the T.
What I'm doing is rip out the T, then paint, then install the visor. May have to touch up a bit here and there, but IMO that's the easiest way compared to the alternatives.
Having said that, It depends on your bucket. I think I'm quite lucky in having a DP97 that accepted some shape changes (flair and dome) and kept them nicely, even with the visor having now been out for a couple of months. I have heard tell of those 97's that spring back to the crappy flat-head, no flair shape if you leave it without a visor for more than a day or two. I guess it depends on how easy you found re-shaping it.
Trial and error is prob the way to go, so you find a system that works for you.
Good luck.
Si