Thanks ktula - it would be good to know as I am always a bit worried when a new beta comes out days after a new software release (usually means someone found the new software screws something up!).
But also please thank Thecus for all the tweaks - looks like they have been listening to gripes even though their support response is awful - perhaps you could suggest they would get better feedback if they acknowledged submissions to their support site.
For info - some observations on this firmware now I have it up and running:
It does seem that access is quicker though I have not done any specific tests (would have had to think of it before I upgraded!)
Disk sleep now works with my Seagate 300MB ST3300622AS's ... so they are much cooler a lot of the time - used to idle at about 45 degC now it is more like 35 degC - but of course it is getting to autumn here ...
Web UI seems more responsive too
Mikkel's (mshapf) SSH module is working fine - I had it running during upgrade and changed root password after upgrade but before reboot.
In general it looks like a lot of the niggles have been fixed and I have not had any new issues.