Mark,
I've done this. I've also documented it to bits with over a million photos. I've written the article about removing the old top and cleaning up the frame. I have all the photos on replacing the new one and lots of top tips. I just haven't got around to writing it all yet.
The long and short of it is that the job is not hard. It is tricky if doing it on your own, but it's easily doable. I could get my finish near excellent by tweaking it a bit more. I am happy with the job I did. It looks as good as most, although someone here has just had a new top put on that looks amazing. It was done by a pro.
I just looked at the prices I was being quoted and felt I could use the money elsewhere. So I did.
If you want to do this, let me know and I can send you a disc of photos. I will,however, be away from my computer for another month.
JH