I bought this unit to replace a Garmin 7200 (7" screen) that I dropped on the floor. I do not like the TomTom nearly as well as the Garmin when it was working. However, after usung the TomTom on a couple of 2,000+ mile trips, I think it is acceptable for use in a big rig. You will almost certainly have to buy a good mounting bracket for the TomTom. The suction cup mount that comes on it is almost useless. I use an AutoDASHMOUNT Portable Friction Dashboard Mount, which is available on Amazon.
the screen is much larger than the 4.3", but it is not as large as the ones you buy at the truck stops. other wise i really don't know what the differences are between those and this one. sorry, didn't realize the computer was on cap lock.