First although we started playing with Alpha about the same time as everyone else (after the second wave of workstations appeared), it didn't go anywhere near production for some time afterwards. In this time, not a lot happened to the hardware but the O/S and compilers stabilised a lot.
Ok, the standards for enterprise level stuff is quite different and a good deal more expensive whatever chip is on board. They tend to have (multiple) good power supplies, good distribution and excellent cooling.
Funnily enough, the lower level systems also seemed to work quite well for us (we developed on them) and used them as specialised intermediate servers). However we usually had headless workstations for that using X from PCs. In all cases though we were running OpenVMS and not Tru-64. The reasoning was that as our primary function was message/record orientated processing rather than byte streams, and VMS was very good at that.
Your hardware downtime does sound quite alarming, but I don't recall any worse reliability than with other hardware. None of the other big sites that I knew were reporting it either. The only real disadvantage was the Alpha's cost against Sparcs.