[jome]

I think rather than a constant difference, I would name a percentage, ie. the deeper the dives in total, the bigger the difference.

The cold and dark (which I have experience with, not so much currents) is something one can train and get used to, but especially for newbies the difference can be quite significant.

I (speaking as a private person) personally think that it is a good idea to lower the requirements a bit for adverse conditions. It is especially important for the first few courses where the students may not have the best possible gear yet and the anxiety and stress is high, being their first time and all. I think 8 meters is pretty manageable in any conditions, but for example 16 has proven a bit tricky sometimes in bad conditions. And it's not just about getting there, but doing it so comfortably that you could actually consider doing it again...

For me it's not the cold so much that get's to me, you can pretty well protect against that with a decent suit. But the utter black darkness, and the thought that you can't see your buddies and they cannot see you, you cannot see what's below or around you and all you have to communicate is the line...It's kind of cool too, being in that "void", but it does definitely shave of a few meters from the performance.

If I'd have to pick a number I'd say 10%, and as far as the course requirements go, maybe round it up so for AIDA* you'd have 1m off, AIDA ** 2 meters and so on...