I have a flyer on my road bike and b17 on the mtb.
B17 is about 15 years old and comfy for up to 6h
Flyer is comfy up to 10h- by which point the rest of me is stuffed.
We did a 100k audax on our tandem last month and it was still fine for that.
On the road it soaks up all kinds of small vibrations and small potholes. I don’t notice it now, it’s just normal to get a smack in the hands and nothing behind if i hit a pot hole.
I don’t do long enough rides on my mtb to need it, I’m shattered long before I need a comfier saddle than the b17.
Why not give it a go? The resale value is good for barely used Brooks.