Garmin Zumo Traffic Receiver

[half man half pie]

Hi, when over in France I use my Garmin 660 in hire cars and my partners as her car sat nav doesnt have euro mapping as its a works car. The Garmin also goes on the bike with the bike mount.
When over in france a couple of months ago I nearly missed my flight as a road had been closed due to works and two cars getting tangled in the cones.
I've looked at the Garmin site and the GTM21 seems to fit the bill for the car so I ordered one with the France subscription from a helpful chap in Peterborough via that well known increasingly chinese based auction site.
So far so good.
Next year I'm looking to spend more time in France on the bike with it occassionally being left at airports and did think that the same traffic info would be useful for closed roads, accidents and a few other issues.  Filtering is good but the orignal sat nav route and arrival time is based on normal road speeds and not filtering speeds.
Having been at the Swiss border in July and September, I do appreiate that some bikes filter at normal motorway speed limits so it wont be an issue for some.
From what I can see, the GTM21 only fits the car mount and some sites recommend the GTM12
Has anyone had any experience of using these in the car or on a bike