A few points to consider:

1. With my IO-550 I can't exercise the (Hartzell) prop below roughly 1900 RPM. Nothing happens. If the engine is out there may not be any oil pressure unless it's windmilling enough to drive the pump and governor. Without high pressure oil from the governor, my understanding is that the prop is designed to go to fine pitch unless it's a feathering or aerobatic prop. I've been intending to test by setting the prop to coarse pitch then shutting down to see where it ended up.

2. My Navion was originally equipped with a 165-HP engine. The IO-550 near idle probably is comparable to the old E-165 at cruise. I discovered this one time when I practiced an engine-out for the Commercial test and found the plane was not descending. We just kept going round and round. Turned out I hadn't pulled the last fraction of an inch on the throttle.
How many HP are required to keep a Lancair in the air? The wing loading is high so speed needs to be kept up but the airframes are very clean. A little bit of extra power may make a big difference in perceived results.

 I think the only way to really know how a plane will fly engine out is to actually shut it down. This is one of those things I haven't gotten to yet but one of these days when I'm feeling brave I'll climb to 10K over my airport, shut the engine down and see what glide ratio I can get.

 One question: what would be the better way to shut down for easy restart? Mags or mixture?  -Bill Wade