I have not taken the course but...interesting they chose to go up to 50% vs. 40% like other agencies. My concern there is since 50% is a common and standard decompression gas, people without proper decompression training (i.e. the in-water skills for bottle handling) might get the idea to bring a 50% bottle with them for "rec-tec" dives and end up botching bottle switches and kill themselves. I guess you could do that with 40% too...maybe a moot point. Time will tell.There online only course for up to nx50 is interesting too...