A quick comment on proofide, my understanding and observation is that the pro models use a thicker leather than the quote regular b 17. I believe also that older Brooks used thicker leather than modern day ones.
In any case, in my relatively short experience with leather sales, 6 or 7 years, I would second the warning of not overdoing putting proofide on. My first b17 seems to be a little softer than my other regular one, and I do think I put more on it and specifically the underneath. It's not overly splayed out, but having bought some other used Brooks lately, I'm going to be very conservative with the stuff now.
I'll stick up some photos are some point.
Doug, given the designed flexiness of the imperial versions due to the cutout, my feeling is to be very sparing with proofide for now.
I've been doing a lot of saddle switching and comparing lately, I will try to do a write up at some point of my views on the various models i have now.
Thanks David, you are correct the Brooks Pro never did soften up. I'll heed your advice with the B17, and wait to see how the break in goes before applying more Proofide. It actually felt pretty good right out of the box.