Has anybody here ever had any experience with these mobile spay/neuter cat clinics?

I have a little stray cat that wandered into the garage one night and attached himself to me (literally! he grabbed onto my leg until I picked him up and held him). He was so sweet and purred so loudly I couldn't resist feeding him, so he quickly became "ours." I want to make sure he's neutered so he doesn't contribute to our area's cat overpopulation problem, but I wasn't sure about the mobile clinics -- they do the operation in the morning, let them recover, and then discharge the same day. (I have two female cats, and they were both quite groggy after their spayings at the vet's office, and needed pain meds -- but I have heard the operation is not such a big deal for the males. Trying to save a little money these days, and the mobile clinic is definitely a cheaper option.)

Any advice would be appreciated...thanks!!