Interesting. Sumatriptan makes me really loopy and slurs my speech. It can also make my jaw ache really bad, which is usually a sign it's working (it has about a 50% success rate for me). I often think that it works by moving the pain from my brain into my jaw.
I never really feel great after taking it, but I'll happily deal with the effects over a migraine any day.
I have an obnoxious clicking in my jaw whenever I chew, but other than that I don't have TMJ as far as I know. I do grind my teeth, but it's sporadic and stress-related rather than a constant thing.
I haven't been able to correlate actual jaw tension, teeth grinding, and migraines in any meaningful pattern. I'd say a good 60-70% of my migraines are due to some mix of brightness, hunger, thirst, exercise, sleep, and stress. Another 10% alcohol, and the rest is random: "Here's the migraine you ordered! Oh, you didn't order one? Well here it is anyway, enjoy!"
I never really feel great after taking it, but I'll happily deal with the effects over a migraine any day.