Julie,
I grew both varieties two years ago.
Noir des Carmes was very productive, and ripened fairly early. Taste was very good. I think I liked them even a little more, eaten warm, soon after picking.
Petit Gris de Rennes ripened significantly later, and produced a decent number of fruits(I only got about four to ripen before frost). These were outstanding in flavor.
I hope they do well for you.

Douglas

Douglas, thanks for your reply.

Like you, I kind of planted these as an afterthought :) I'm just happy they are growing at all. My neighbors think I'm mad to be growing melons out in the open and not in a greenhouse. Oh well, I hope I can prove them wrong.
One last question. Does Noir des Carmes have tendrils? The vines aren't very long yet but still they have no tendrils at all, whereas the PGdR are just miniscule in comparison and are already sending out little tendrils.

Mmm..nevermind my previous post. After tying up the NdC vines they produced tendrils. I only tied them up two days ago...coincidence or just what they wanted? Who knows.