In general, people like free. Since you are in SW, I assume you know this already. While I don't proclaim to be an app guru, I have used quite a few and this is the first app that I have seen using this model (free for 30 days). The majority of apps have 2 versions- 1) the free, limited functionality, ad-based version and 2) the paid, no-ad full feature version.
As far as why I don't try it? I don't want to be coupled to a time-frame. Outside of installing it and using it for 2 minutes, I may not have a need for it (ie, go wheeling) within the trial period . When the event arises that I do want to use it, and its outside of 30 day period, that would be an annoyance and I would uninstall it. So, I never really did get to try it out to see how useful it is, but now I am being forced to to pay for it to try it out- that's a turn off for me. I don't have a problem upgrading to full versions that I like, but just don't couple me to a time. This is one reason why you don't see many 30-day trials on apps. Make sense?
I like your permissions, or lack thereof, that's a BIG plus. IMO, model the functionality after the 1st gen 4runners.
What if he coupled it to hours instead? Turn it on when needed, then turn it off. After 10 hours of accumulated usage the app asks for upgrading.
TY
PS: Looks nice.