Hi,
After trying Xandrox I believe it is not any better than plain minoxidil. Also it's more expenmsive so there's no point investing more for it. How ever, I do think 12,5% and 15% are more effective due to their high concentration of minoxidil (and there aren't versions without azelaic acid).
I believe that it's would wiser to use plain minoxidil. To combat DHT, if someone wishes to do it toppically, I suggest that he spironolactone or fluridil which are probabely more effective than azelaic acid.
Good luck,