OK -- being a confirmed DIR agnostic, I'll stick my nose into this.
1. Bob's entirely correct -- don't preach, do.
2. Why do YOU dive with a 7 foot hose? Is it "just because" or ? Sometimes "DIR" divers, especially new ones, latch onto the equipment aspects of "DIR" without appreciating what I believe are the most important aspects of "DIR" -- team diving and safety.
3. DON'T BELIEVE ANYTHING TSandM WRITES regarding being hasseled or made fun of by her PADI instructors -- I know, I was there!
4. I'm doing a PADI DM class right now using a 40" hose and bungied backup. My partner agreed wholeheartedly that doing air shares, especially swimming buddy breathing, was MUCH easier with the longer hose. If you are out with some non-DIR friends tell them at the beginning of the dive you may want to practice an air share with them. They will be amazed at how easy it is (back to Bob's no preach, do).
5. If your rescue class buddies don't understand the concept of SAC rates (and they've probably never been introduced to them) ask if they have air integrated computers (like the Suunto Cobra) and if they do, ask if they've ever looked at their computed SAC rate (or RMV). Either way, this become a teaching moment, especially in Rescue, for everyone to understand basic gas management. (See Lamont's PDF regarding this topic -- I printed it out and gave it to my DM buddy AND my DM instructor.)
But most of all, HAVE FUN and don't NOT dive with "strokes" -- just show them how much fun it is to be a safe(r) diver even with those blessed split fins and dangling consoles.
[Note to Doug, Bob and Lynne -- I HAVE NOT gone over to the Dark Side!!!!]