I have the new square type and once I finally get totally sick of this thing I think will get the rcbs tool to replace it. I really don't like it. Never tried the old style but it had to be better than mine.
Have you tried Ebay? There are a couple up there right now.
The old round one I had was great until I broke the thumb handle. This new square one is a piece of junk! I hate it and I don't want to pay fifty dollars for the RCBS! On the other hand Ebay is your friend.