I do belive in the begining that the Russell was created by Bill senior and at some point he sold out to Russell with a noncompetition clause in the deal. After that expired Bill senior went back into building saddles but used all foam instead of the spring like the original. After he died his sons carried on in seperate locations. Both seats are good options so it amounts to which one puts a smile on your cheeks. My cheeks like the Russell.
Shame about the sibling split.
Rick used to have a section on his web site where he explained that he had experience building sprung seats, and then also explained why he didn't recommend them.
This seat stuff is very personal. No one else can tell you which seat you're going to like the best. Even if you get to try someone elses seat, it won't necessarily tell you that much... because theirs will have been broken in by them, and they're different from you.
Corbin makes good seats, but folks often complain about the company's level of responsiveness to customers who need a bit more help. (I've had good customer support from Corbin myself on a couple of their seats).
Sargent makes good seats, but folks often complain that their foam is hard to break in. (I've had no trouble breaking in a couple of Sargent seats).
I've ridden Bill Mayer saddles that were built for others, and it was obvious they weren't built for me, so I wouldn't be a good judge of them.
On this seat stuff, everyone needs to work the problem for themselves and then hope for the best. Some guys end up going through two or three custom seats before finding happiness. I don't know how it can be avoided.