I ride our demonstrator regularly and the suspension is ok on the road or for light off-road work down a gravel road. It's a pretty sturdy built fork overall but a bit soft for my taste like most bikes are (the Superdual is even softer by the way, but has more suspension travel). It's doing a good job for me with the occasional gravel & sand track but if I would use it offroad regularly I would eventually look into something aftermarket. For the front maybe heavier fork oil and redoing of the seals might already do the job, for the rear there are heaps of options available in the aftermarket world if you want to go down this track.
In general you get a lot of bike for the money on the Silver Vase, but they are built to a budget like almost any bike. They are fun to ride and have a great "old school" feeling to it and the engine likes to rev and is very torquey. For the price you get them you can easily spend a little bit and make it suitable for what you need it for and you will have a great bike that is light and does everything well.
Take one of them for a test ride if you have the chance. The Gran Milano is a totally different ride btw with its 17inch front wheel and upgraded suspension. The Gran Turismo would be very similar to the Silver Vase (same setup with different tyres). Pity you are over East you could test ride both back to back with us here in Perth 
Hope this helps you, good luck!