Barkstar wrote:
But 5ft or 6ft its still in his way and you could easily hide a bike, pedestrian or dangerous debris behind it.
You could, but then again you could just as easily not. As I said
in a previous thread on this subject - "without evaluating each installation from the exact point of view of the driver, it's not that easy to judge how much forward vision they're losing - if any at all"...
Since that thread I've replaced my old factory satnav equipped Omega with a newer satnav-less one, and so have joined the TomTom club. As a result, I can now update the pics in that earlier thread with some featuring a real TT, showing
exactly how little forward vision may be impaired with a dashtop location.

These two pics show almost exactly how little forward vision I'd give up by having a TT sat atop the dash, either directly in front of me or just off to the left.
This pic simply drops the camera a couple of inches, representing the eyeline of a shorter driver, or someone my height who drives with the seat lowered even further than I put it. In this example, the loss of forward vision would give me cause for concern,
but notice that the TT itself hasn't moved at all, illustrating my original point about drivers eyeline being all important.