I'm starting to experiment with pure O2. I want to see if it has a positive effect on lager fermentations. My ales are great, but it might save me some time. I'm not sure I'd switch to O2 for any of my Belgian styles, though.
I got a welding tank and a low flow medical regulator off of ebay that has the welding CGA-540 fitting (yes, they exist). I get a lot of foam at 1 LPM, so it seems to me like it's basically a waste of O2. According to the BYO article that has been posted a few times, you theoretically only need 60 seconds at .2 LPM to hit 8 ppm.
I'm going to do a side by side experiment on a German pils that I'm brewing this weekend. I'm aiming for 12-15 ppm, so one carboy will get 90 seconds at .25 LPM, and the other 90 seconds at 1 LPM.