I'm not an expert. The following is opinion. Once you get to gas mixes involving greater than 40% O2 its a wise idea to use equipment prepared for O2. First, recognize that your tanks should be O2 cleaned (no oxidization, whether steel or aluminum) along with your tank valves. With respect to your regulators, O2 cleaning involves ensuring that no tiny particulate is inadvertantly trapped anywhere within your regulator, that there is no oxidization or surface irregularities, and that there are no tiny nicks or burrs - nothing that would be disadvantageous in a high oxygen environment. Second, (while there is disagreement on the topic,) its generally considered prudent to replace all internal components such as the high pressure seat and o-rings with products better suited to high O2 environments (such as viton). While there are conflicting opinions, IMHO this goes in spades for any decompression regulator that will be used on an O2 bottle. (Just remember that you may need to switch regulators around due to one failure or another, either on your rig or a team-mates....so ensure that all your regulators are capable of meeting all the team's needs. Many of my friends essentially own five identical regulators, in fact, most of my friends use 5 Apeks regs. I use 5 Scubapro regs.)boogeywoogey:
In terms of 'best' regs, as you know, thats a loaded question. Many technical divers use Apeks, they have the advantage of being endorsed by a number of outspoken divers with considerable reputations. I use Scubapro and have never felt at any disadvantage underwater. Atomics are excellent regulators. Aqua-lung regulators have good reputations. Some would suggest that an even better design for cold water use might be the Poseidon Xtreme regulators - they have a geometrically reduced number of moving internal parts, something ridiculous...and the design in fact derives from a valve used in handling bulk oxygen; a stainless steel ball closing down at the apex of a stainless steel funnel or cone. It's clearly a personal choice - however, I have two additional points you may wish to consider. First, with respect to annual maintenance, it is much easier to purchase tools and spare parts to maintain your own regs with Apeks, for example, than it is with Scubapro. Go ahead, ask me how I know this.
When you are maintaining 5 regulators or more of your own annually, it is prudent to select a reg you can purchase the parts and tools for. Second, your regs are not really "yours". They are team gear. This sounds trite, but its true. It makes a great deal of sense to dive 5 of the exact same regs that all your buddies are diving. You can get parts from a buddy in remote locations, if someone has issues you can interchange regs without problems, and all in all its simply one less thing to worry about if everyone uses the exact same regs. So I'd advise that you purchase whatever the rest of your team is using.FWIW.
YMMV.
Doc
