Just anecdotally, I went through the seat issue a few years ago for the same reason - numbness. Found the Selle SMP and thought it would be the end all/be all. Got one, the numbness went away felt great - really great - but by the end of a 25 mile ride, not so much. By mile 100 (multiple rides) I hated the thing. Felt like my package was getting extruded through the seat.

Switched to a Koobi - same idea but less radical. Much better. After 150 miles, and when it broke in (they warn about the break in period), had a similar issue but not as bad and found that a Koobi worked well on my mountain bike where you are not as static. My wife has a Koobi and loves it.

Finally settled on the Fizik Antares (the middle one) Versus with the relieved channel down the middle but no hole. That seat also feels quite different after 100 miles. Just got a new cyclocross bike (adventure bike) put one of the Fizik's on there and it felt funny. Rode it for bit more than 100 miles and it feels a lot different. Starting to feel like the one on my road bike with thousands of miles on it (about 5K).

Also, the more mileage that you do, it changes too. Ride 20 miles, things can be fine. Get to 50, you may hate the seat. It takes a bit to fully "explore" the seat - at least for me. Maybe I have a sensitive a$$, who knows?

Seats change as you break them in (more or less, depending on the seat). So after the thousand dollars or so I have into seats, those are the lessons I learned.

J.