a bike bought came with a standard B17, but the lack of setback adjustment-range
and a zero set-back seatpost had me get rid of it, in a trade..

Its replacement, a Fizik Brompton-Vitesse that offered the set back adjustment range..

I have a 30 and a 20 year old brooks Pro they are just fine..
I took care of them well over the years, even rode long tours on them ,
under plastic bags, in foul weather .