I always take salespeople's comment with a grain of salt unless you have a longer working relationship with them.
The 9B SST has lower power ratings than the Sherbourn and can't be compared. All Bryston are monoblock designs like Sherbourn. I have a 16 year old 4B 2 x 250w, 20 year old 3B 2 x 125w, 19 year old 2B 2 x 60w and they all sing better, with detail and soundstage than my 2 year old Rotel RSX-1065 5 x 100w.
In the end go with most power you an afford(your comfort factor). Amps are something you will be keeping for sometime(Or so you hope).
