I've been struggling with exactly the same thing when looking at a possible kit purchase.
The Mk.2 MAUW has been raised to 544kg due to new internal wing engineering stuff when using the Rotax engine. In that configuration you could comfortably fly 2 85kg adults plus 42kg (60litres) of fuel and not worry at busting your insurance.
I concluded 520kg on the Mk1 is really too prohibitive unless your machine is 300kg when empty. I suspect the LAA chose to reduce all UK versions from 600kg building in extra safety but it does seriously hamper the desirability of the machine, especially the Mk1's.
With either version, 2 up plus fuel, the capability of carrying light (it will have to be) touring kit sadly etc isn't there. Which is a great shame, given the Trail sells itself as a utility aeroplane.
Looking on AFORS, there is one Mk2 being built stating MAUW of 560kg. I have no idea how they got this figure provisionally agreed.