Good information, thanks for sharing! I check out the WorldNav and the Teletype reviews and information. They have navigation specifically for trucks which Streets and Trips doesn't.
I use P C. Miler 18 Haz-Mat routing and street level mapping but it's not as good as an actual GPS system. Yes PC Miler is expensive but it's left over from our trucking company other wise I couldn't afford it.

I guess I'm old fashioned and like good directions and a map. I noticed something I was doing that bothered me. 
Instead of using the map as I always have I found I was using the PC Miler so much that I had a hard time getting back into using the map. If you don't keep a current map and the GPS goes down for what ever reason then you have a headache like I did. I guess I haven't gotten interested in having GPS yet. It's still a little expensive for my blood LOL.
Thanks for sharing the info.