- my U5 with 2.0.1 kept crashing every night in "low-duty" periods,
       with varying kernel error messages - sometimes even with RED STATE
       and SIR Reset messages that pointed to hardware issues


FWIW, i would not usually say that RED STATE and SIR Reset are
indicivative of hardware issues.  infact, "SIR" = "software
initiated reset" and is usually caused by one of these:

phat-bass ~> grep -wn sir /sys/arch/sparc64/sparc64/locore.s
195:#define NOTREACHED  sir
567:#define     UTRAP(type)     sir; VTRAP(type, slowtrap)
873:    sir
897:    sir
923:    sir
1116:   sir
1140:   sir
2349:   sir                     ! Just issue a reset and don't try to recover.
2622:   sir                                             ! Force a watchdog
2652:!  sir                                             ! Force a watchdog
2819:!  sir
3402:   sir                             ! Just issue a reset and don't try to recover.
4793:    sir                                            ! DEBUG we should NOT have any usable windows here
4915:!  sir                     ! WATCHDOG
4944:   sir

or very occasionally by one in the prom.


.mrg.