I love Corbins and have had them on many bikes, including a CRF250L, although always purchased used as I can’t see how they could justify the new cost. They do seem to have a fairly common problem with the bases not being 100% perfect in shape resulting in the covers chafing against the frame or bodywork in one or two areas, eventually wearing through the cover material. They must be lined with lead as they are incredibly heavy compared to stock seats.
Agreed. I had a Corbin on my old CBR1000F; lovely and comfortable, but the build quality was atrocious and exactly as you describe, the base chafed through the cover in a couple of places. Can't complain as I got it from a bloke in Southampton who sold me the seat and a pair of original mirrors for £30. Those were the days.