In reply to Chris the Tall:
> My ski boots are now over 10 years old and the liners are trashed - do I try and get new liners or replace with new boots ?
Depends, on theboots you have, how good of a skier you really and how often you ski.
> Has boot tech changed much in last 10 years?
Yes.
> How long should a pair last?
Depends on use, liners generally pack out in 2 to 5 years for and avid skier (10 to 50 days per year). Boot backing and touring wear out the liner quicker than just pure skiing.
> The boots have never been super comfy, but various tinkering over the time frame have made them bearable. The fear of going back to stage 1 and having to get a new pair right is partly why I'm reluctant to change.
Get new boots, and start with a pair that fits (shell fit) and heatmoldable liners. Oh, and these Freeride boots are something to consider as well. Walking switch and nice (partial) vibram sole make life a lot nicer, even if you never venture in the back country... Unless professional super G is your thing, in which case why an earth are you asking such a question to beging with.