Joel, Jim,
I agree with you both. Bigger flies better and is easier to see.
Joel, you seem to assume that bigger means glow powered and
that's not true anymore. Is the question why aren't there any
glow powered gyros? or why aren't there any large gyros?

A big model used to have to be glow, it doesn't anymore. Many of the new modellers in
the hobby came in from park flyers and are now moving to .20 and .40 sized
electrics due to the dropping battery prices. If you have nothing to start with
and want a .20 sized plane here are the get started costs:

Electric: hacker a20-20L $60, 25 amp speed control $50, 3 cell 2100 $70, charger $50 = $240
Glo : OS 25 $80, servo $20, fuel pump $20, glo driver $15, gallon fuel $20, 12v battery $20, starter $30,
12v charger $10, receiver battery $15 = $230

Glow engines seem less expensive to people that already have fuel pumps, glo drivers, 12 volt batteries and chargers,
spare glo plugs, glo plug wrenches, field box, paper towel holder, cleanser, a can of fuel proofer, thinner
to clean the brushes after fuel proofing, brass tubing benders, fuel line, etc., etc., etc.

To the person with nothing to start with the glow option is just as expensive, doesn't perform any better,
causes the person to have to join the local club and drive across town to the field to fly, is messier to clean
up and requires a lot more expertise to get to run right. From our perspective, we had to fly glo because it
was all there was. To fly glo we had to have a big field where the noise was away from neighbors. To have
a big field we had to join a club and AMA and get an FCC licence (KVL9782). Then we could fly a high performance model airplane. We got used
to it. But to these new guys they have better performing airplanes than we did, that can fly in the park, with no
noise and no cleanup. We bought all that support gear for glo because we had to, just to be able to fly at all. These
new guys don't. The only remaining advantage to glo, the sound of the engine, is the one problem for flying in the
park. Most guys won't put up with all the hassle just to hear the sound of the engine.

For me, I build small electric models because you can build them
fast and test them fast. If I had to go to the field to test it would take
forever, my field is an hour and a half round trip and I can only go once a week or less.
My test runway outside the house I fly on every afternoon or morning.
Now that I've figured the gyro out I'm going to make a bigger one, but it will
be electric with a gas option. When the electric one flies I'll strap on the
glo motor and take it to the field with a much higher chance of success.

Thanks for the interesting topic.
mickey