I had an X64.4 Dac from 1995 to 2001, powered 24x7, no issues.
I currently have:
- a Wadia 9 (2001 - current) pwwered 24x7, no issues
- Wadia 7 with GNC mods, required an alignment and door belt replacement (partly due to sitting in 100+ degree unpowered house for a month afer Katrina) - thanks to GNC for the repair.
- Wadia 2000T (1995 - current) has some issues initializing a disk (I need to install a new teflon bearing supplied courtesy of GNC, but haven't gotten there yet)
So my problems have been minor and with older mechanical items, nothing unusual in my opinion. The 2000T dates back to around 1993 and the 7 to around 1996.
In my experience the Wadia gear is very reliable.