At the end of the day people are always going to have had bad experiences with all the various tuners, there's threads all over with mud slinging from well respected tuners aimed at each other,
You'll always get Somone who wants more than the mapper will advise or the car can take so when it goes bang they'll blame whoever mapped it. Not the fact that they ignored the advice from Mr x etc etc.
Any monkey with a laptop and cable can attempt to map, (no offence ment to anyone or our primate friends) once they have the basics understood, doesn't mean they are any good, years of experience count for alot obviously, hell I'm in the process of learning about my esl, but there's no way I'd say I could tweak a map for someone or offer my services to anybody, just cos I have the cable
I'm doing it purely because I'm interested in my car and how it works,
At the end of the day we all have our prefered garage/tuners, I take most of the stuff on the Internet with a pinch of salt.
Do your research into your chosen tuner, don't let Internet bunfights get into your head and ask people who you know for recommendations.
I chose Martin to do my work because he spent 20 mins on the phone before I bought my car telling me what to look for and what to avoid etc. I'd never seen the bloke or used his garage before, but because of his willingness to answer my daft questions I had no problems with trusting him with my car,