I have always assumed that perforated release film is for wet lay and non-perforated is for prepreg, as stated in the descriptions of the materials on EC's site.

However, I have just been discussing this issue with the Technical Director of a Composites manufacturer and he said:

"For oven cure (of prepreg), perforated release and breather gives best results".

I assumed that perforated would allow resin to leak out, but this appears not to be the case. It is all about getting the air out of the whole composite. For small items up to, say, a car door, then non-perforated is fine (but he would still use perforated), but larger projects (like my roof for example) he recommends using perforated for best results.

Opinions?

Follow the directions of the specific pre-preg you are using, there are massive differences between different pre-preg systems which means if you are asking one manufacturer for advice on another manufacturers product then that advice may not be relevant. 

Lots of pre-pregs do use a perforated release film, it's very common and probably more 'the norm' than unperforated. However it depends a lot on the resin viscosity of each pre-preg system, and how long that resin flows for before it gels as to how much resin will bleed off into the breather. This is even as complex as making changes to the cure cycle making perforated vs unperforated beneficial, like if you were going for a fast cure at final cure temp with no ramps or dwells then you may benefit from having a perforated to help get air out quickly before the resin gels. There's certainly no blanket rule that applies to all pre-pregs.

Just checked with my prepreg supplier and they are recommending that I stick with the perforated release film, even at 80 deg C.