Air assisted suspension

I'm considering getting this. Has anyone fitted it or had it fitted to a T4 chassis in particular, or indeed any motorhome?

If so,

Which make/firm did you buy from?
What did the kit consist of?
What was the approximate cost?
Was it easy to fit?
Did you get a guarantee?
Has it been reliable?
What benefits have you found?
In your opinion was it worth the money?

Thanks in advance for your comments.