I'd like to thank everyone for their input, especially those who provided their real-world experience. Currently I am experiencing some issues with foam cutting the wing cores for the c-130. So, progress on the test stand and engine testing is on a momentary hold for a week or so. It's been a little interesting to sit back and read differences in opinions on the propping question! I think there are a few people who misunderstood the original intent of the propping question, so let me clarify some points.

1. Using a four bladed propeller to look more realistic is a goal only if thrust can be maintained at an acceptable level.
2. Lowering the engine RPM is a goal in as much as I fly (take-off too) my scale ships at around half throttle (T-28, P-51, P-47, etc.) and I see much wasted potential at higher (unused) RPMs that do little for the desired scale speed - high speed may be great for P-51s but does not do much for transport planes. Ya, I know, I may be out of the most desirable power band but I don't have time to stroke and re-time the engines
3. An associated goal of lowering RPMs is to lower prop speed (noise) and to lower the exhaust note and perceived frequency (again noise).
4. Available multi-blade (3-4 or more) props on our model airplanes will lower efficiency, however, speed is generally most affected by this efficiency loss and thrust to a lessor degree.
5. There never was a free lunch. So the inevitable inefficiency, power loss, heat build-up, transition issues and idle problems are all balanced against noise gains (desired sound) and desired RPMs. Yes, there is only so far you can go!
6. No, this thing never will sound like a full scale C-130 - I hope that fact is just too obvious. I'm around them enough and live in the approach path of the only C-130 air base that routinely serves both the North and South poles (last I checked). So I have a good idea what they sound like.

The simple answer to all of this is larger engines (52FS not 30FS) that can turn the less efficient but larger four bladed props at a more desirable RPM (no, I didn't say cruise at 2,200 RPM). Of course one of the trade-offs here is weight and fuel consumption - no free lunch. "More realistic" does not mean "exactly as", but closer than what you have now!

Thanks again to all who contributed and please keep the info coming!