XD53 has a 53mm driver which is the biggest headphone driver available at the moment and delivers higher and lower frequence's then the HD25 and the most un-enhanced bass, the HD25's have a 40mm driver i believe and while im sure they can produce good sound, its not as vast as the 53's done a shit load of research comparing the 2 before i got my 53's
i think your mainly talking about the MK3's, the MK1's have been reported to be very flimsy at times and werent built very tough, and if you bumped them the CD could skip or freeze...but the MK2 was a big improvement on this and the MK3 better again
what they said ^ most places will have different things, my main big club here has 2000's, 1000's, TT's, DJM900 and my smaller local club (better place anyway) has 850's and djm800
until you change your mind again mitch, if your just gonna learn then get rid of them and buy TT's just buying some cheap CDJ's...there are sooooo many 800's around for like $300-$400 each, thats nothing