I'm a current 4th year at UTMB and say, take the money and run. You will get essentially the same education, with a lot less beatdown. I've talked to many UTSW students on the interview trail, and boy, they are beat down all 4years, but mostly third and 4th year where they work their assess off and are practically living in the hospital!! UTMB atmosphere is more laid back and doesn't suck the life outta you, so you can still have a decent social life. Houston is an hours' drive, and you can go there every weekend if you like.
As far as getting a good residency, trust me, UTMB students get into some of the most competitive residencies all over the nation. Go to the UTMB website and look for the match list for residencies for the last few years. It's not the name of the school, but what you put into it. And UTMB is a good name. Board scores are the best in Texas because we get more time to study as our system based learning lets you concetrate on one system at a time, and probably works better in the long run as evidenced by the board scores. I think alot of premeds are so stuck on the UTSW name or the Baylor name, but in the end, trust me it does not matter. And if you are interested in research, there's plenty on the island.
You go to any school and have crappy grades you won't get any competitive residency anywhere. You go to most american schools, bust your tail, you can get in to competitive residencies at many desirable locations.
So forget "what's in a name", and take the money and run. 120k is a lot of moola!!! Take it from someone graduating with more than that in debt. Come 3rd and 4th years at UTSW I guarantee that you will SURELY REGRET YOUR CHOICE. Seriously, get over the UTSW thing and make the smart choice.
Good luck.