Here's an interesting article on Israeli submarines that I though was worth a link. While the Israeli submarine force is often credited by idiots on the right with being able to transcend time and distance, everything I've heard is that they're a pretty good coastal defense force. My boats didn't work directly with many foreign diesels (at least not cooperatively), so I don't have that much direct experience, but I was impressed in the few instances I did with what the more advanced diesel boat operators could do with their limited capabilities.
Do you have any good stories about working with OPFOR diesel boats? Which country do you think does the best job? I've always heard the Chileans are right up there near the top. I'd say that, maintenance-wise, the Canadians would probably have to be near the bottom.