FWIW, the combination of limiting the PEP to binding expressions and the motivating example of sequential if/elif tests that each need to utilize an expression in their body (e.g. matching various regexen by narrowing, avoiding repeated indent) gets me to +1.
I still think the edge case changes to comprehension semantics is needless for this PEP. However, it concerns a situation I don't think I've ever encountered in the wild, and certainly never relied on the old admittedly odd behavior.
Yes, binding expressions in the current PEP support an extremely
limited subset of what Python's assignment statements support.[...]
Guido's if/elif/elif/elif/ ... complex text-processing example didn't,
but because the current lack of an ability to bind-and-test in one
gulp forced the `elif` parts to be ever-more-deeply-indented `if`