How many have actually done this?
quite a few.
How long does it last?
2 to 5 years or more depending on how well you care for it.
How much does it cost?
Depending on how big, how much, how indepth you go...3-5k
Will it damage the gel?
How long to apply?
Depends, but should only take a couple of days.
Will it stand up to salt water/rough water at 70mph?
Yes, no problem (refer to bellow pic).
Can you apply over existing paint/vinyl?
Yes you can apply over paint. Not a good idea over vinyl (it'll leave raised edges.
Anyone had any luck?
I've never heard anyone say anything but possitive comments about wraps.
Yes, you will be able to change the look of your boat every 3-5 years for the next 20 years for the same price as one custom paint job.
The Graphics Co. (www.thegraphicsco.com) did our boat and did an excellent job. We've run it in salt and fresh water over the past season and a half with out problems.