Guys,
If you upgrade to 6.1 then don't use any backup system files as these will cause problems as I have discovered.
Now cleaned system and re-installed all programs and everything working great. Benefits so far (for me at least):
1. Supports SDHC cards above 4 Gb (I have a Sandisk 8 Gb Mini SD card).
2. Task Manager - this lists all running programs with memory and CPU usage. This is where you now close any open programs rather than querying memory.
Haven't compared power but would not expect any great difference.
Have checked GPS and works perfectly. Skype is causing a problem but will try to identify why this is and report back.
If anyone wants to know anything else then please ask.
Sandymac