GW has NO idea what a sniper assassin is. This is my idea of what a true Vindicare should be: choped the head of a Space Marine scout, glued on the Vindicare's, then added part of the Vindicare's gun to the scout's.
In addition to what the others have said, I would like to see a more dynamic base. I don't think a sniper would be sitting in the middle of a gravel pit / road. All in all I like the model.