>Would not matter as far as I can see. The whole contents of that table has to be read.
>
>If you look at the execution plan when a CTE is used, you'll see that CTEs are "in-lined" into the query - they are not materialized and stored. While not a hard and fast rule, CTEs are likely to be a tad more efficient (though the user is not likely to notice any difference)

I very much doubt that. Both have to be scanned internally to process the query. I don't see much difference here. It probably needs a very large set before any difference would show either way.