I trained in Canada where they taught the wing down technique. When I got back to the UK I was made to use the crab technique by RAF QFIs. I continued with the latter until I got to ETPS and subsequently onto B Sqn at A&AEE. During my time there I did a considerable amount of work on landing techniques where I was given carte blanche to try what I liked. My findings were conclusive - wing down is far superior. OK, so you land on one wheel, but you are still, in fact, still partially wing bourne at this time. Advantages are as follows: the fine judgement on when to kick off drift is very difficult to get right and, if you don't, the ac will land with crab on which can significantly stress some ac. In strong, gusty X winds, with wing down, you land with the control deflections which are exactly what you want for the roll out which prevents the arm and leg blurr that usually follows a crab touch down. It is easy to land without drift because the instant of touchdown is not critical and so is a much smoother. I have used this technique with ac ranging fom Slingsby T67s through to VC10s taking Comet and Lancaster en route. The only ac not suitable for this treatment are things like 747s A340 and B52. Incidentally, I have fair experience on both A320 and B737. There is no mystery - they both handle like normal ac. In fact I found the A320 a little nicer to handle manually than its rival. (Retire to WWll bunker at the end of my garden). As you may appreciate this is a big hobby-horse for me, but I do wish the RAF had been broad minded enough in times past to get away from sacred cows and try different techniques.
p.s. I never ground looped a Harvard and so have disproved the old saying "There are those who have ground looped a Harvard and those who havn't yet"