Dude, there is no "downside" to self tuning, Do you think anybody who learned how to tune was born already knowing how to tune ? Lol, be the difference to your "own" car, you're the one driving her, not xxx tuner or tuner shop. Some people prefer to get a custom tune with whatever professional tuner package of your choice whether it is HPT or EFlive, then they customize it little by little, some others would start from scratch, even after having their own cars tuned.
When i started out, i did it with a POS tune from one the big names in tuner shops in the market. After the experience with them and more than a grand "wasted", i was able to tune my car, and by far exceed my custom "Pro" dyno tune, and i didn't even keep any settings from them either, it was basically a new start, my car was cammed at the time, and had full exhaust. I didn't have any previous tuning experience whatsoever, i just read a lot, and had the will to learn and become pro efficient in tuning so nobody was never going to sell me crap ever again.
Granted, you don't pick the skills in 3 nights, there is a learning curve to it, but i don't know anybody who "didn't" learn how to do it, after actually getting themselves into it, we see more engine/trans getting blown up by some of this "Pro" tuners than when the "rookies" do it by themselves. Yes, there are bad tuners, and good tuners out there. some have the good luck to get the good ones, some others doesn't, that's just the way it is sometimes.
How do you know what good is good, sentiment ? dyno bs numbers ? there is a difference between knowing what a good tune is, and another one pretending to know based on opinions, just because the car run, or post good times in the 30-40F weather, doesn't mean it's an "awesome" tune, Do you know of any car that doesn't run faster the colder it gets outside ?
lol how do you know 2 glasses of water in front of you won't taste different if you don't try them out first ? They both look like water from the outside