Shiny, everyone has their own comfort level about travel and safety. Like anywhere there are 'bad' areas in every city. I think we've had 10 murders in my city this year and they were all drug related. There are areas I would not venture alone in. Same with TJ.
My experience: Get picked up at the airport in the OCC. Its a six lane freeway to the border, then a six lane boulavard, high volume traffic travelling fast for a couple klicks, turn right enter a secure underground garage. The clinic itself is a fortress, all doors locked buzzers to get in and out etc. OCC Van to the hotel, again same major blvd to the hotel. Excellent location also security conscious. OCC Van to the airport. The only dodgy area is probably the blocks around the SD airport. Lots of homeless enjoying that warm weather. lol
If you google Nuevo Laredo, you'll see its on the opposite end of the border over by larado texas, they have a completely different set of problems. There are pockets of trouble along the border but there are good areas too.
There have been some good threads on this. someone posted a map of TJ with the trouble spots. check that out.