Comments on both:
I've tried the ocean reef for about an hour in a pool and ended up buying an interspiro.
When you compare the two side by side, the interspiro seems like a sturdier piece of stuff. I bought the black/non positive pressure one. When wearing it, it does seem a bit more enclosed than the OR but thats to be expected because the OR has much more clear plastic and the one i tried had a light blue skirt so that also let some light in i'm sure. Plus the black just looks so darn cool (and fashion has to be at least a small consideration when buying gear, i think).
One thing you'll want for sure is some form of surface breathing device which i still cant believe the interspiro doesnt come with. As i recall, you could just unscrew a port in the OR mask and that would let you breath surface air. However, with the interspiro, there is no surface breathing mechanism that comes with it. As far as i know there are only two available - the Gill which gives a new glass and a vent by your temple and something from sartek called the surface breathing valve (SBV-1 i think is their name for it.) The SBV is the one i ordered (havent received it yet) and seems less obtrusive as it goes straight into the area where your mouth/nose are housed. What i found without that device is that you wear it on the surface, pre-dive, and as with all regulators its takes a bit of work to breath with out of water (not too much though.) So this does tend to get you into the water with a bit less air to start with depending on how long you stay out of the water. Plus it also gets you into the water in a less than relaxed state and thus your air consumption seems to go up. Looking quite forward to getting the SBV.
The one thing i kept thinking with the ocean reef is "damn i've got a lot of stuff in front of my face". The 2nd stage on the ocean reef seems to stick out a mile. I think you can place it on one of the side vents if you wanted to but then it comes back to the fashion thing again. I like the unobtrusive nature of the placement for the 2nd stage on the interspiro. Gives your face a much smoother profile.
As far as wearing both of them, i found them to both give a similar experience which is quite unlike a normal mask/regulator combination.
The main reason i bought the FFM was because of the communications ability. Unfortunately, the comm gear wasnt going to be delivered til the end of oct which places me around the time when i'm likely to curtail diving for the season, so i cancelled it and cant comment on that aspect.
Thats about it. I love my interspiro.
steve