A properly sealed surface doesn't necessarily mean it will profusely bead water. All sealers will bead after application and slowly lose the beading ability over time, some faster than others. This is not a good indication of whether or not it is still working well.
511 does a great job with beading and initial performance. It is very possible things have changed over the years, but I despise this product. It has been known to generate a film, attract dirt and yellow lighter color surfaces. 511 was a huge portion of the sealer used where I am at and we had a real problem with white marble and limestone floors that were sealed with it. This is over the course of the last 10 years, and I haven't dealt with one for a few years, so if they changed their formula in the last 5 years or so, then it's likely not an issue anymore.
A lot of people love 511 and that's fine. If it works for you, good. You want to use a great sealer? There are many to choose from.