I was injured 4.5 years ago and I am a T-10 paraplegic. I had very bad spasms as well. I was taking the maximum dosage of baclofen as well as zanaflex and valium at night to try to get some sleep. I was amazed at the relief I felt after the trial as well, but I decided to go ahead with the surgery.
I am athletic and very active and the pump has never been an issue. You can see the pump, but it does not cause any issues.
As far as your concerns with infections and refilling the pump, I think I have some information which might help. The initial surgery is actually the main risk of infection, but since the pump is place in the subcutaneous level (just under the skin) the risk is low. The refill is done with a single injection. The risk of infection is very low. I am a T-10 and the injection site is below my level of sensation, so since you are a T-6 it should be pain free as well.
The baclofen has a life expectancy of six months at body temperature, so that is the longest you can go without having the pump refilled. (they remove the excess medication in the pump then fill it with fresh) When they adjust and/or refill the pump, they can print out an information sheet that has the expected date the pump will run out at the current dosage. I usually set my appointment for the refill about a week before that before I leave the doctor's office.
It has made a huge difference in my daily life and how I feel. Of course, it is a decision you have to make for yourself based on your own situation, but I'm glad I got mine. Good luck with your decision.