as for the fitting maybe they never charged me more because i had my system fitted? i thought the list price included fitting. Oh well looks like i got a good deal 
They say money goes to money...

When I can afford the Purefreedom system, it will definitely be a consideration.
Need to see how this system gets on, as running a 1 man set up, and occasional useage I think will be fine, where the Webasto based systems come into their own is reliability, they work 24-7 in some applications, so it's a no brainer.
Looking forward to being able to sleep a bit though, knowing I am going to get out to work every day, rather than waking every couple of hours and looking outside, wondering if its going to freeze, should I have done this or that....