Vent mount for Garmin Nuvi

I think it depends on the vent mount you are looking at. I have this one and it sits about 2 inches off the vent. http://www.mountguys.com/product_p/mfx47-nuvi.htm
I have had it for over a year and their are no problems.

There are others that sit on the vent like this one http://www.mountguys.com/product_p/gn047-350.htm which may not be good if you have the vent on high AC during hot months or high heat for cold months.

Thanks for the info I am in the market and appreciate the info.

I looked at the vent mounts and some are hard to move from one vehicle to another. I went with the bean bag and it is great for my jeep , yukon and the motor home. easy to take out and easy to hide when parking in a lot or on the street. also it gives more options to where and how to use. You also don't have to worry about the heat or the cold.