Have both the Hema HN7 and VMS , the VMS worked ok the street map worked well but the Offroad maps were clunky at best ,it had the software glitch and was forced to buy the HN7 because of time constraints on our lap of oz .
The Hema off road maps work and are better than VMS there is also many different functions that make this unit superior imo to the VMS such as Bluetooth and I love the index function which moves the map not the arrow so for someone that gets lost in a car park like me I know the direction of arrow is my travelling direction and tracks on the left are tracks on the left etc .
The street map on the Hema is garbage and unreliable but it's a third party function not owned by Hema just licensed by them .
The VMS did shit itself with a software glitch but I eventually got a patch from them that seems to have fixed it and it still works after six or seven years .
My Hema has been back for repair twice and is about to go back again and all for the same fault the battery ( or so they say) .
Talking to one of their techs I was told their batteries last between 6 and 18 months on average depending on use and I never seen this fact anywhere on the box or from the salesman at ARB .
I do prefer the Hema though although there are some inaccuracies their maps and functionality is superior .