Well, I have one that I've only bench run (so far). I didn't use any pressure line, just pure carburetor draw and it seemed to work fine (well, the engine was a little bit sensitive to the fuel level in the 50 oz tank of my test stand, but I don't think anyone would use such a huge fuel tank in an airplane with this engine ). I left the nipple on the case open to the atmosphere.

A couple more pieces of advice: if you want your engine lo last, make sure to have castor oil in the fuel. Do not run on pure synthetic oil, and in any case don't lower the totale oil content below 20%. Also don't get crazy on the nitromethane level: the engine runs very hot, and too much nitro is not helpful in this regard (I mix my own fuel, and my wankel gets a special blend of 5% nitro, 10% synthetic oil, 15% castor oil and 70% methanol). For this same reason, make sure the engine has lots of cooling air available (no tight cowls and/or oversized spinners).
Finally, the engine likes small props. Don't go beyond 10x5 and you should be fine.

If you are interested, [link=http://it.youtube.com/watch?v=3LhmBdra1NE]here[/link] is a video of my engine on the stand.

Almost forgot: when you install the muffler, make sure both screws are on tight. I had the front one come loose during the same test run in the video (it was after I finished recording the video) and fall right on the spinning propeller, clipping off one of its tips and being thrown sideways at about warp 3. The screw-bullet didn't hit me, but it was not a nice experience.

Hope this helps,

Radial.