I second what SmT and Doclach have said, but here's my 50c.
There are loads of helpful articles online about the differences between the two cores and here is just one example written by Factory 7 frontman, Derek Footit. Just click on the link and have a read.
Equipment Series > Bodyboard Cores
For me the choice between the two is down to personal preference. I used to always ride boards with PE (Dow) cores until about 2 years ago. Coming from Cape Town it seemed like the logical choice. PE is suited to cold water, as you obvioulsy know, and I always thought that a board with a PP core would be way too stiff - until I tried one.
I now only ride PP core, and that's on the West Coast. But I am itching to try some of the new developments coming through where shapers are combining different types of cores to construct a hybrid board. You've probably heard of a few like the type Doc mentioned as well as the Dual, and now Triple cores...
The reason I choose to ride PP is performance. It's lightweight, the PP boards I have are thinner than my PE boards and I get enough flex out of the PP core to enjoy my surfs. PE boards just feel bulky and heavy since I started riding PP boards. But a huge thing to consider when buying a PP board is that they apparently don't last as long as PE boards (I suppose if you ride like a pro that might be the case, but still it's worth pointing out), so if you're looking to be on the same board in 2 years time then you might want to opt for the longer lasting PE board.
In my opinion the water temp at Caves probably won't have much of an impact on a PE core. It might get a little more flex on the really warm days, but other than that it won't be too much of a negative. PE cores do not last in places with water temps like Durban. I once went up there with my trusted Mike Stewart Mach 7-40 (Dow core), and it was like riding a banana. I came back with a kazillion deck creases.
Pick up the phone and give Derek a call...he knows way more than I do and like Shaun says - they've got some insane specials on at the mo.
