Finally got around to changing/trying this out. Bought the Superman weights/tool off of ebay. First off I just realised that I only ordered 1 weight instead of 2 -- oops. Anyway, just tried to the tool and removed one weight with no issues. The other one, in the heel, isn't budging at all. In fact the pegs on the tool that i purchased seem to bend and one fell out! Doh!
I was trying to go to 15's from 20's because I increased the length and wanted to see if there was much of a difference. Anyway, I'll soak it with some lubricant and see if it loosens up. Once thing I did notice was a good bit of sand coming out of the one side I was able to remove.