Fresh Step is very good at controlling odors, but it is dusty. No matter what they claim, all of the clumping litters are dusty. I don't think anyone wants to go back to clay litter and the only other non-dusty litters I know of are Feline Pine (original, not the clumping version) and Yesterday's News, which is made from recycled paper. As you probably know, they aren't the best at controlling odors of solids.
Since they are all dusty and I am able to put the litter boxes in what I call the cat room (it is supposed to be my office/crafting room) I use Worlds Best because at least it isn't supposed to be toxic if it is on their paws and I don't find it as dusty as others. I don't really know if the other dust is toxic, there is a lot of literature and conjecture saying both yea and nay and I think dust of any kind is not good.
I think if odor control is your primary concern, I would try Fresh Step.
BTW, I don't believe your pans need to be replaced. I've had mine for years and they clean up just fine. I always smell the bottom and there is never an odor and it sounds like you clean yours often and well. I bought the large boxes that Lowe's carries b/c they are large, a pretty sage green and only $10.00.
If you find the perfect litter (no dust, great odor control), let us know!! It might be out there, I've tried many but definitely not all. If $$ is a big concern, you can get 42 pounds of Fresh Step at Sam's Club for $14.47 and WalMart sometimes has special packs of 38 pounds for around $12.00, plus Fresh Step has a points program. Both Fresh Step and Worlds Best have coupons pretty easily available. Good luck!!