I use a standard automotive-style GPS, though the primary navigation is more pre-planning my route beforehand and the GPS is more for tracking and for getting back on course should something go amiss, like I miss a turn.
A GPS makes a great servant but a poor master. A trucker GPS should have options to avoid low clearances and unsuitable roads, but the effectiveness of those options is limited by the quality and thoroughness of the database it has of bad roads and low clearances. You still have to pay attention on your own.
I generally try to avoid taking my motorhome through dense urban areas on surface streets. Sometimes it is not possible to avoid that, but it is hardly fun in any case.