my work league last year switched to a format like this (probably in part due to me having multiple quality RBs on my bench the previous sesaon)... I lobbied against it but to no avail
it was alright though, a different strategy than my other leagues... we pretty much had a starter and a backup at every position so if there were 2 starting RB slots, then 2 backup RBs... only 2 backup spots for the 3 WR though you had the option to use of the backup RB slots for a 6th wideout... personally, I think it places too much emphasis on the draft and thins the free agent pool too much at every position but RB...
as an aside, if you use yahoo or a site where players don't go on waivers once games start on Sundays, I can completely understand the complaints although that's a separate matter... it's understandable if a person gets pissed if someone swoops up all backup RBs of players who get hurt, sitting with a laptop on Sundays as this takes no skill and foresight... but again, this is a separate issue because I see nothing wrong with stocking up on RBs using a waiver system to make claims after Sunday games..
also, I think 7 bench spots is a bit much for a league with your starting lineup... I guess it's preference but I prefer closer to 5 bench spots to force owners to make some difficult decisions.. it seems to me with 7 bench spots, there really wouldn't be many tough decisions at all during the season for most owners as to who to drop when you pick someone up..
All of my analysis is based on PPR