Being a NAUI CD I am a bit bias to them but the additional cost of being cross certified is only about $150 as you only need one insurance policy- just make sure its one that covers both agencies there are many. If you want to teach with your friends shop a crossover to teach should be an easy step. Having done many crossovers for PADI instructors I do find that most have to study up on physics and environment (review the NAUI Master Scuba Diver Text) as they do poorly on this part of the exam as its covered in more detail than PADI.
Curious to those that think the training materials for NAUI are lacking - the Scuba Diver/OW kits are some of the best texts books I have seen and the new online stuff is great. As will all things I can see some room for improvement but I find them much better and more student friendly than the PADI ones (which are not bad but could do with less ads). (The advanced book is lacking in a big way I do admit). Rescue, Master and Nitrox I think are very good. I have not reviewed the new Rescue course on line yet so can not speak to that.
Curious to those that think the training materials for NAUI are lacking - the Scuba Diver/OW kits are some of the best texts books I have seen and the new online stuff is great. As will all things I can see some room for improvement but I find them much better and more student friendly than the PADI ones (which are not bad but could do with less ads). (The advanced book is lacking in a big way I do admit). Rescue, Master and Nitrox I think are very good. I have not reviewed the new Rescue course on line yet so can not speak to that.