Interesting question Mark. Check out the pollen SEM images - they both look the same as we would expect. It should be just as effective I would say but if you were to grow hybrids from the fruits you would get a different lighter colour range with 'Constance Eliott'.
Myles

Here is a link that might be useful: Passiflora pollen SEM images.

Myles,

Beautiful pictures. However I'm not sure if I could tell the difference between pollen that is definitely not OK--say that of a caerulea tetraploid or a sterile hybrid.

I take it that lack of flower pigmentation, although very visible, is an arbitrary reason to expect that 'Constance Eliot' would be any more or less fertile than other forms of caerulea with minor differences here and there. Is that a reasonable statement?