I have a Spoon on my MTB, and it was very comfortable right away - without any of that feeling that it needed to break me in first. I use my MTB with slick-ish tyres like a hybrid too, so it's not just strict off-road use.
I find the Spoon very comfortable up to about 40-50 miles, but at that distance I start feeling a bit of bum pressure, and I wouldn't want to go much beyond that.
For longer distances, my Brooks Cambium C17 comes into its own - my biggest ride with that was 105 miles this year, and I still felt like I was in buttock heaven (though I was actually in Birkenhead). But the Cambium is four times the price of the Spoon, and if I didn't regularly ride more than 50 miles I'd have Spoons on all of my bikes.
This is without any padding in shorts, etc, which I've never used.