Can't comment on 2-3 years use. I've been using it more like 25, the first 10 of which were pretty heavy and totally against what would be deemed sensible and safe practice. I still have a blast maybe 1-3 times a year.
In my opinion it's bollocks. No loss of 'magic', there never was any magic to lose its just chemistry plain and simple. The thing that goes missing over time is the novelty, the wonder that a little pill can make you feel like that.
I've had some great nights over the last five years but instead of 'wow this is amazing' its more like 'this is fucking excellent'. Last year we had one of the best nights ever - and that's some tough competition. Get the drugs, music and atmosphere right and its as good as ever. Maybe try candy/hippy flipping or touch of K just to change it up a little?
This is more or less exactly my experience. Spot on with the novelty thing. The effects of MDMA never change but everything else does. Or rather they did change - and dramatically so - and then they tend to get stuck in a bit of a rut one way or another. Often a very pleasing rut but a rut nonetheless. If "magic" is required you need to put yourself in and around new and exciting situations, places, people and so forth. They say familiarity brings contempt but I find it mostly just brings mediocrity.
I think Treacles posts are pretty much spot on tbh - It was not about finding your sweet spot , it was taking stupid amount of MDMA because it was piss cheap and great fun (reckless, dangerous YES of course). I've been in the game a while and I still love MDMA.
Also this. I never noticed any correlation between reckless abuse of MDMA and supposed loss of "magic". Around the time I joined BL I was IVing 3.5g of xtal a week (well, over 2-3 days anyway). Had fuck all to do with "magic" it was just pure hedonism. I have no desire to use those kind of amounts anymore and personally find a couple of decent pills is plenty for a night now. "Magic" still in full effect and long may it stay that way

