Here's what I said about the issue in my Fundies report:
http://www.scubaboard.com/forums/dir/340216-fundies-report-dutch-springs-10-a.html#post5316608
"-Doubles vs. singles - I had wanted to take Fundies in doubles. Bob didn't exactly say no, but he made one of his trademark faces when I told him I had never dove them before. So I split and plugged my brand new doubles into singles, and dove singles instead. I have mixed feelings about this. On the one hand, given that I passed and dove doubles competently the next week, I think that allowing myself to improve skills without adding a new and major piece of equipment was probably the right call. Who knows how difficult it would have been diving doubles while learning everything else, and I may well not have picked up on many subtleties because I was so absorbed with learning how to dive the new kit. On the other hand, I'm still not at all happy with my hose routing, and having Bob's genius sense of how to route the hoses and the exact positioning of the bands on the tanks and so forth would help immensely. However, I'm sure I'll get it sorted out, and will even likely run into Bob at the quarry some time when he gets back from teaching abroad and take advantage of his incredible generosity in sharing his time and knowledge. If I had to do it over again, I think that, as always, Bob was right and singles was the correct choice."
http://www.scubaboard.com/forums/dir/340216-fundies-report-dutch-springs-10-a.html#post5316608
"-Doubles vs. singles - I had wanted to take Fundies in doubles. Bob didn't exactly say no, but he made one of his trademark faces when I told him I had never dove them before. So I split and plugged my brand new doubles into singles, and dove singles instead. I have mixed feelings about this. On the one hand, given that I passed and dove doubles competently the next week, I think that allowing myself to improve skills without adding a new and major piece of equipment was probably the right call. Who knows how difficult it would have been diving doubles while learning everything else, and I may well not have picked up on many subtleties because I was so absorbed with learning how to dive the new kit. On the other hand, I'm still not at all happy with my hose routing, and having Bob's genius sense of how to route the hoses and the exact positioning of the bands on the tanks and so forth would help immensely. However, I'm sure I'll get it sorted out, and will even likely run into Bob at the quarry some time when he gets back from teaching abroad and take advantage of his incredible generosity in sharing his time and knowledge. If I had to do it over again, I think that, as always, Bob was right and singles was the correct choice."