I just saw this thread. I've been using my tronxy "A8" for about a year now and haven't had any significant issues. If you have questions/problems with your tronxy let me know, I'll try and help. My upgrades have been:

new printed x-axis ends and carriage with Auto Level Sensor
Chinese e3d V6
Y tensioner

My only failure so far has been the MOSFET for the hotbed, but I soldered a better one on. The Melzi board isn't ideal, I will admit.