Meedley - in regards to people doing what works for them, I see it like this:
There are always fluke occurrences here and there where someone is able to perform perfectly well using a technique that is atypical from the norm. EVH holds the pick with his middle finger and thumb, Marty plays with his thumb nail, etc. But if you are a developing guitarist, that doesn't mean you should emulate those fluke situations because 99/100 times it won't work for a person, whereas the well documented 'proper' way of doing things works out at the highest percentage of the time. If you wanted to make a bunch of money, for example, you could go to college and get good grades and take internships and get a business degree and so on - following the documented path for best results, or you could just try really hard to win the lottery. It will happen in some scenarios that the conventional path won't work out for someone, or some slob will hit the lottery and feel wholly justified in that plan - but that is very rare - you're better off playing the percentages. To advise a developing guitarist to 'do what feels right to him' is the same as saying 'hope ya hit the lottery', to insist a developing guitarist follow conventional wisdom is saying 'here is your best percentage shot at becoming a proficient guitarist - no guarantees, but still the best choice you can make'. Every time I've followed the 'I'm going to do this how it feels right to me' strategy, I've wound up at 'uhoh, hit a brick wall and now have to unteach myself this and start over doing it properly'. Everything from bad wrist posture to thumb over the fret board, to holding the pick too deep along my index finger, to refusing to alternate pick (remember that back in the day? People would always start yacking about James Hetfield as justification for never alternate picking) - all of that turned out to be a waste of time. I'm sure every once in a while a person will fluke into doing something in a way that defies conventional wisdom and pretty much only works for him, but does end up working. But it is not worth the 99/100 other times you abandon conventional technique and wind up realizing in the end that it's simply not going to work the way you opted to go. The existence of anomalies does not justify hoping to be one yourself - we all have to make decisions based on our understanding of probability to give ourselves the best chance of things going the way we want them to go.
In terms of the tapping, hey if middle works for you that's fine. I brought it up because I moved away from middle specifically because I found limitations on it personally, and then the index finger solved those limitations. Of course there is no way to really know for sure which one of us is the anomaly and which one is on the path of best probability (since there are a decent # of proponents of each on either side). Or it may be the case in this instance, that the probabilities of success with the middle finger vs success with the index finger are extremely close and it doesn't really matter between them. I wanted to mention it because I think most people tap with their middle finger in part because they never thought to tap with the index finger and never thought of working on that pick tuck to make it available - it never crossed my mind until I saw the MJR video. It's worth giving a genuine try to if you have not tried it previously, because it MAY wind up being helpful to developing guitarists.