Lots of folks here have, or have had, all three models. I can address the pickups on the Paul's Guitar and 408, but haven't had a 513.
The idea behind the 408 pickups (this includes Paul's Guitar that has the 408 neck pickup and a version of the 408 as the bridge pickup) is that the narrower ones sense a smaller part of the string, and thus "hear" more like what a single coil pickup hears. So the tone is a little clearer and brighter than most humbuckers when in humbucker mode, and sounds like a true single coil with no volume loss in single coil mode. The reason there's no volume loss is that split, a certain amount of winds (1500? someone correct me) stay on from the pickup that's nominally split off.
On the 408, the bridge pickup is wider, and the tone in humbucker mode is more traditional than it is on the Paul's guitar.
The split coil sounds sound a lot like the humbucking sounds - just clearer and brighter, a little less meaty, thus behaving like a true single coil version of the humbucker. Some people expect the sounds to be very different as with most split coil positions on a humbucker, so if you're after very different sounding splits, that's something to think about.
Personally, I love the 408 concept and the way it works. Still, the tone isn't necessarily what I'd call "vintage-type output on the humbuckers." It's clearer. It's significantly more open, and almost closer to a single coil in some ways. However, the humbucker positions have more thickness than the splits. I don't want this to sound like the 408s can't do traditional 'bucker things, they are simply more open sounding than a vintage humbucker with its phasey rolled-off top end.
I have vintage style humbucker PRSes for what they do.
For truly vintage type output on the humbuckers with great coil splits, I'd suggest also taking a look at the McCarty and the DGT.
As I said, I haven't had a 513 so can't address that.