I had an alpha (miata, AKA Personal Workstation 500au, I think) running NT on my desk for a while, while we waited for space to open up in a rack..(1) The NT on it seemed quite usable, thanks to the FX!32 emulator. When running x86 compiled stuff, it felt mostly as fast as contemporary high-end PCs, once you'd opened the x86 program and used it for a while.
(1) We used FreeBSD/alpha, so we always bought the "NT" version of machines to save $$$ on the DEC UNIX license fee. Eg, just like today, the Windows version of a machine was cheaper.. FreeBSD did not support the ARC firmware needed by NT, but you could easily switch the machines to SRM in order to load FreeBSD.
(1) We used FreeBSD/alpha, so we always bought the "NT" version of machines to save $$$ on the DEC UNIX license fee. Eg, just like today, the Windows version of a machine was cheaper.. FreeBSD did not support the ARC firmware needed by NT, but you could easily switch the machines to SRM in order to load FreeBSD.