Thanks for the replies,
That is a good point about the versatility, it would be nice to position it for better reception or take it with me when I need to. I may end up getting a portable antenna just for those reasons alone.
Although I am still leaning towards something more permanent for the truck such as the window mount or maybe a larger external whip antenna mounted somewhere else.
As far as window mounting goes, all the side windows on my truck roll down so it pretty much forces me to mount it on the rear window.
I guess the big concern I have is I would attach this thing to the window with adhesive only to find out it didn't help at all and then be stuck with it there.