O2 cleaning is largely hype. Any reg, right off the shelf, is most certainly fine for 40%. Perhaps even 50%.
If you're going to use it with 100% O2, you can get it O2 cleaned very cheaply -- or do it yourself. O2 cleaning involves the following:
1) Disassembling everything and cleaning thoroughly, under a magnifier, with a suitable degreaser like Simple Green and suitable lintless cloths like microfiber.
2) Replacing normal greases and lubricants with O2-compatible lubricants like Crysto-Lube.
3) Replacing rubber O-rings with O2-compatible O-rings made of Viton or Nitrile.
Unless your local LDS has a clean-room, they're only going to oxygen clean your reg to a specification recognized as any sort of "clean" only to the diving industry. As soon as you throw the reg in the dive bag or put the reg on a tank that's had it valve touched by human hands, your reg is no longer oxygen clean.
Many people make too big a deal about oxygen cleanliness mainly because they realize there's money to be made. In reality, no one really has clean regs, and it doesn't really matter, anyway.
IMO, all that's necessary is that you follow those three steps (only takes a half-hour) -- then you can use your reg for any mix you'd like. I'm sure this is going to get flames -- but before you flame, please consider including some references that specifically indicate what's wrong with what I've said, on a practical level.
- Warren
