David, I bought a DTXtreme III 10 yrs ago. The software is upgraded to DTX950, so the kit is in effect a 950, except for the pads.
I upgraded my snare to the DTX pad in 2019, and the stick response difference is well worth the money. The Toms I'm happy to continue with for the time being (I have 6, so upgrading will be expensive).
As for repairs, I haven't had problems with the hats, but I have successfully repaired two kick pads. If your kick problem is the plastic core cracking, see my other thread relating to repair of the kick pad. It was another forum member who explained how to fix my pad, and his advice was so effective, I have now successfully fixed my original KP125 and the spare I bought, which was also cracked.
Re: Roland v Yamaha, I agree with the above advice. Stick response and voices give Roland the edge in those particular areas, but the DTX pads are almost up to the level of the Roland mesh heads in terms of stick response, and the versatility of the Yamaha system (sampling) gets you around the voice update issue. The main advantages are above but there are others, one of the main ones for me being the ability to expand the kit - I now have 16 outputs, which I am sure is not possible with Roland- and while the Roland system is a seriously well playing and sounding system, I'm very happy with my Yamaha DTXTREME III and wouldn't switch.