It appears there's another new alternative closure solution on the market, at least one that's new to me: the AS Elite, produced by a company called Guala Seal (also known as Ardea Seal). According to its manufacturers, the AS Elite is "probably the best stopper in the world." While that remains to be seen, I will say that it does seem to present some potential advances over other plastic/polymer type closures.
I was recently surprised to find a Guala Seal stopping up a bottle of Burgundy, not a Passetoutgrain, mind you, but a $30ish sub-regional red Burg from a reputable estate-based producer in the Côtes de Nuits. I've never known this producer to utilize any type of non-cork closure in the past and was a bit perplexed that they chose a mid-level rather than entry-level wine for its introduction.
In summary, I'm less than thrilled with the look and feel of the AS Elite. I've never particularly liked the aesthetics (or performance, for that matter) of any of the plastic/elastomer family of stoppers, but this somehow manages to look even more artificial. From a performance perspective, though, I'll try to keep an open mind and will be curious to see how the Guala Seal stands the test of time.