My guild uses the SK system and loves it. However we use the list for only mainspec pieces. If a piece gets no bids then all offspecs roll on it. To aviod issues, if you are seen wearing a piece you rolled on for offspec while raiding in your main spec you get thrown to the bottom of the list and possibly forced to stay there for a while (or worse). We really don't like loot whores in our guild, they aren't tolerated. We also use a separate list for tier tokens, to avoid people siting at the top of the list just to get tier. In this way the tier tokens are given in a very linear manner, after you get your token you have to wait until everyone else there gets one before you get your second one. Its a very fair system, we haven't had any major loot issues since we went to it at the beginning of wrath.

Back on topic of the original post. I see offspec's working how they always have in wrath. Your offspec will generally be one tier below your mainspec, until the current tier is on farm. Run the current tier to gear out your mainspec, on off days take your guild to the previous tier raids for your offpsec, no lockout issues to deal with. I really don't see any complications with there only being one lockout. You may get offspec gear slower, but so will everyone else.