I've also installed them about an inch + proud of the front of the countertop; for two reasons.
- The seam between the countertop and front edge of the sink looks better they meet at the straight edge of the sink rather than the curve
- The other concern is faucet crowding at the back end. Most of these sink are obviously pretty large. I've found that trying to make the front end flush not only looks bad but also makes the faucet look really cramped in at the back. That extra inch or so of space helps give the faucet some space. Just, aesthetics but some worry about that sort of thing.
I don't know how you guys support these sinks. I install a plywood platform supported by 2x's inside the base cabinet. I also add a layer of waterproof membrane, usually a piece of roofing membrane (since I usually have a scrap role laying around) to handle any condensation between the plywood and sink.