I am in a slightly different position (prostate surgery) but same end result is it was/still is a bit tender. The Selle Italia Max and Flow ranges have some with very large cutouts and I found an SLR Superflow good on my road bike. Didn’t have so much of a prob on the mtb because of a slightly more upright riding position.
They are expensive, if your mate is anywhere near Cardiff he is welcome to have a try-out of it. I think with a big cutout it is very important to get the width of saddle right for your sit bones, as all the weight will be on them – mine is a narrow 130mm type as I have narrow hips, if your mate is wide-arsed (as it were) then he might need a wider base.