I tried an ISM PR 2.0 earlier this year, after I started having numbness problems with my B17 Imperial.

It's worth a shot, but you need to follow their setup instructions to the letter. Also, you need to ride on it 'square', not to one side - many people ride to one side on traditional saddles. IOW, you need to give yourself some time to get used to it.

Their theory, which works for me, is that you don't spend all that much time riding on your ischial tuberosities; rather, you spend most of your time on your pubic rami. Therefore, sitbone width is a minor concern, if it's a concern at all.

ISMs appear to have a nose, but appearances are wrong in this case. Be sure and check out the medical images at the bottom of the setup page. The rear section of the ISM is deceptive, too. Ischial tuberosities should be placed in front of the widest portion of the seat, and the arms/horns fit about half way into your crotch - dangly bits ride in front of the arms, and soft tissue behind the dangly bits ride in the cutout.

In the end, the PR 2.0 didn't work for me, but it clearly works for a lot of people. I suspect my excess weight may cause problems with the ISM I tried.

If the ISM you choose doesn't work for you, I recommend trying out a Selle SMP saddle. (I'm on a TRK because it was cheap.) Way different from the Brooks. I've been numbness free as far as 20 miles without a break. (I've done several 25-30 mile rides without numbness, but those rides have always included some sort of interruption in butt-on-the-saddle time.) With the SMPs, the dangly bits ride in front of the dip - see the diagrams in the US patent application (sorry, I don't have a link).