Well if you want to get a T1 go right ahead, as people have said before, as soon as it's outside the ISPs network it's out of their control. You are NOT going to significantly reduce your latency that way. When I get back to work on Wednesday from visiting family I can ping from Redmond, WA to whatever city you'd like on T1, FiOS and Comcast and I'll be willing to bet they'll easily be within 10% of each other, which is easily within a margin of error for that test.
You seem to have already made up your mind, even with multiple people telling you otherwise.
As for 100ms being bad for gaming; I've managed to come out top of my server on 70% of the multiplayer games I've played this weekend. On a 4G tethered connection that's unreliable and shitty as hell.
Great. I can top-3 on shitty pings too, but it's not fun and it's frustrating as hell when the only reason the other guy got the better of you was because of high latency.