A few hours after I made the purchases it crashed again. I left it until the parts had arrived and were fitted, on booting, no network connection - the last crash had killed my onboard NIC! Just got a wireless dongle, gotta tweak my Services back down, upgrade security on the network, etc..
The M4's still on the 0309? firmware but a quick check with HD Tune showed 210MB/s before fitting the dongle, now seeing only 120!
Boot times (Windows takeover to opening TaskMan) down to sub 16 seconds, was in the range of 42-52 seconds with the spinner. Best result = near silence, no db meter but the difference feels pretty staggering! Some slight lag felt on opening certain programs, not studied patterns yet but I suspect the lack of ReadyBoost (I had 8GB with the HDD) and prefetching or the older firmware may be implicated here.
So, still some work to do but very pleased so far :thumbsup2: