Here's the link for that product:
http://www.gpscity.com/ram-mount-wat...ake-mount.html
I haven't used it, but it seems to have gotten mixed reviews. Some don't like that it is much bigger than the Nuvi (it slides around in case unless you make a foam cutout). Also some report difficulty viewing in direct sunlight through the box.
One of my personal requirements for installing anything on my bike is that it is waterproof. I don't want to have to worry about anything or have to pull over abbruptly if it starts raining.
When I was choosing my GPS about a year and a half ago, the Zumo's were about $1000. I opted for the previous generation of water proof GPS units from Garmin. I got a Garmin Quest2 for about $300. They are still in Amazon Marketplace for $350. They don't have all the bells and whistles of the Zumo, but they still work well for half the price and are waterproof to the same specification as the Zumo.
I have mine installed in a RAM mount and it is tied into the bike's electric.
It has worked well for me for 32,000+ miles. Only real complaint is that on-the-fly route creation is painfully slow. But I enter all large routes in advance from my computer anyway so that is rarely a problem.
When my quest finally gives up the ghost, I'll probably upgrade to a Zumo since they have come down in price.