I have one of the Garmin mounts. The vibration issue is trivially sorted by putting a little bit of tape inside the mount so that the bracket fit is snug. I've been using mine for about 18 months and have had no problems at all. The RAM mount is a bit of a monstrosity IMO.
This is the one you want. Your vista should have come with a little clip that fixes to the battery cover - this slots into the mount.
The RAM one is certainly "chunkier"....but it does have one advantage:
Both the bodge and the dedicated clip-on can be fitted to the stem as alternative to the bars.
As my bars are crowded enough as it is, and I use a long stem which is otherwise unoccupied, that does it for me.
Can't remember exactly what time I hit the order button but:
Order confirmation e-mail received 10:29 am yesterday
Order despatched e-mail received 10:33 am yesterday
.... and there's me thinking "yeah right"
Well they arrived 1st class Recorded Delivery this morning.
Thumbs up for "BuyBits" - even if they do have a stupid name!