When I was long ago working on a revision to Superworld, we discussed the notion of success values, before the project got abandoned.
I re-evaluated the design elements once more during the writing of BRP, and abandoned the notion again for the following reasons;
It was a radical departure from the current system, and I didn't want BRP to be incompatible with previous editions of BRP-based products.
In my opinion, the mechanics broke when applying them to skills above 100%, especially when using skills radically in excess of 100%. For example, a character with a skill of 150% would automatically score at least 5 success levels, no matter what he rolled (assuming he didn't fumble). The notion of having to accommodate that level of progression for result charts felt impossible. It didn't scale well with settings that allowed skills of over 100% and those that didn't. By contrast, the normal special/critical system continued to work fine.