Hmm dno if this helps - but you can work your way around this by using the auto signup system.
I had similar issues to you guys, but have removed this by using the auto signup system.
What I do is I use all scheduled raids with raid roles - I have then created a raiding roster where ppl have allready specified their preffered role.
I can now see my entire raiding roster at each raid which gives me a full view on how many healers, tanks etc we have ready for raiding!
If members wanted to swap spec which many did with Lich King, they simply edited their character so it was showing something different for me in the overall picture.
Maybe u can use the above, otherwise I'm sry I made u read all this
NOTE - if you do use the auto signup system you will have to link the scheduled event to your new raiding roster. Also you can't set it so that they are awaiting approval with this system, as all will be approved right away.
A positive side note is by using a system like this you force all members to notify you if they will be attending or not - this was a huge problem for us in the past.