The thing about an RV GPS is it's designed to find the best route from point A to point B based on the criteria entered (size of RV, road type preferences, etc). And most GPSs do this dynamically based on traffic and can also re-route you if you make a wrong turn.
If you export a fixed route from any piece of software (RV Trip Wizard included), you are taking away the dynamic routing ability of a GPS and dumbing it down to just be a fancy map. Additionally, if the software exports a "trip" as just the start and end points, it's no different than entering the same destination on the GPS. So, not a lot of added value unless you have a lot of stops, or are exporting your entire vacation as one trip. But that just gets messy.
For us, a GPS "trip" is one day's travel. We put a ton of stays (usually several months out) into RV Trip Wizard, but are only worried about navigating to the next location for that day. So, we have the location entered into the GPS the night before and just click go in the morning. And, since we have the same location already in RV Trip Wizard, we use the RVLife App as a secondary GPS. Just click on the destination and go. Simple one-day navigation in both apps, backing each other up in case one gets wonky.