I have spot varnish on my 460GT. A few things to consider.
Your print environment needs to be immaculate and dust free for it to work well. Any tiny tiny tiny bit dust that lands on the wet layer leads to imperfections that are really visible!
Your print time will jump hugely using varnish, first pass is a light layer with lamps, 2nd is a wet layer with no lamps, 3rd is lamps only, so your standard print takes 4 times longer!
It is only really effective for doing small spot areas, not designed for doing a large or complete flood coat.
If I was buying again I would probably avoid varnish unless you know you have a good flow of work to use it and a great print room to run the machine in!