"Took an angle grinder to the seat...
......but it is much lower and it does not pitch forward anymore! Whether it will be comfy on a long ride remains to be seen!!!
Just a few comments regarding the process....
Removing the seat cover is easy.
Peel back the rider seat foam - it is only glued at the front.
Be very careful with the angle grinder/wire brush, it works really well but only use VERY light strokes as it can (and did) catch once and took off some foam I did not want to remove!
I used a hole saw to enlarge the small hole under your spine - I am told it works well and is helpful
The seat foam is very soft and squidgy... and very thick. I removed LOADS... (from the underside) leaving a 2.5 in air gap under the seat foam / seat pan. I partially filled this with much denser (at least 2X) closed cell foam but left a 1.5in air gap. I made a bum shape similar to an old tractor seat. The denser foam was glued in place and feathered with the grinder.
The top of the seat foam was not touched at all.
The result is a much lower seat (1.5 inch) with less but layered denser foam. I hope it will be enough. If not, it is easy to modify. The larger hole in the seat pan relieves a bit of stress on the bottom of the spine and the denser foam spreads the load a bit. When sat on, it feels more like I am sitting in it rather than on it and I feel more upright. The sliding forward sensation has gone because the rear has been drastically lowered.
I have also bought an Air Hawk cushion as "insurance" and I had that in mind when I removed so much foam. The addition of the Air Hawk should not increase the seat height above stock now.
Anyway, it is an easy job and quite enjoyable.. I need to buy some stainless staples to finish it off but if needed I will happily repeat the process with different foam.
I shall report back with results! Time will tell if it works...