Ok made a few hills with mine yesterday - as I had a day off with the kids as it now school hols for my lot.
1) Board is quite strong but marks fairly easy. Therefore you will need to be fairly careful especially if doing above mat pieces. Mine are going to be below a mat so no real issue.
2) Very easy to cut and sand. Used a coping saw with no problem, however I ended up using my power saw for speed and ease.
3) Use a fine toothed saw as possible otherwise you can get bumps and indentations or a rough cut that i shard to really sand out. I use 15tpi coping saw and found that it generated a very rough 45 degree cut. One reason why I switched to my power saw which has a very fine hacksaw blade.
4) Sanding and cutting does create a lot of mess / dust.
5) I would like an easier method to create a slope cut rather than using a freehand power saw
Only played with one 30mm board so far - but I will be getting more to make some more hills.
any other questions happy to answer.