I currently use 4000s and Krylions (now called Pro4 Endurance). I get better flat protection and mileage from the Krylion, although it is marginal.

The 4000s rubber seams softer and stickier, and junk can get on them and gradually work their way in. I still get occasional flats with the Krylion, but they tend to be a single poke from a long wire rather than a slow bore from a tiny shard.

I still wouldn't expect moving to either to more than double your mile between punctures, so you still might want something tougher.