>I've yet to see an example of a single application which is faster in x32 than best_of(x86,x86_64)
That is the wrong metric to judge an ABI by - unless you agree that we should stick with an x86 + x86_64 biarchy indefinitely, and have distributions compile every other application appropriately. Then we really will end up with both sets of libraries pinned in memory.
x32 is noticeably better than x86, on some benchmarks as much as 30% more. It is also noticeably better than x86_64, another 30% on important workloads. It is a better all around ABI for most applications.
x86 is stunted, and will hopefully go away in a few years. But x32 sounds like it is worth keeping around for a long time. A 30% performance increase on many workloads isn't the sort of thing you want to idly throw away.