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This interesting email is from Kevin Kimball and describes his experiences with various propellers. 

We have tested and compared many propellers on the Pitts Model 12.  These include V530 2.4m 2 blade Russian prop, Hoffmann 3 blade, Whirlwind 3 blade, MTV9-250-27 and MTV9-250-29.
The V-530 produced the lowest thrust at 1320 lb on our equipment.  It also has the greatest vibration of a the props tested which may partially be turbulence from the tip vortices of the square blades.  This is the lowest cost option for M14 props but the supply is becoming limited.
The Hoffmann 3 blade tested was a 2.4m prop as well.  It produced slightly more thrust than the V530 at around 1400 lb.  It is a very smooth prop with little vibration.  The leading edge protection is softer than some of the other 3 blade props and the spinner choices are limited.
The Whirlwind 3 blade tested was 2.5m diameter.  On our test rib, we saw 1510lb static thrust.  A nice 18" spinner is fitted to it for good looks.  This type prop was first used on Yak 55 aircraft with good results.  When we tested it on the faster model 12, we had some difficulty resolving a prop lag sort of issue.  This prop may be out of production at this time.
MTV9-250-27 was the standard 2.5m Sukhoi prop which we used on the model 12.  Thrust was measured at 1560 lb and it performs great throughout all speed ranges as if connected directly to the pilot's brain.  A very good prop.
MTV9-250-29 is the new "wide Chord" version of the 3 blade M14P prop.  This one produced approximately 8% more thrust than the -27 blade pulling 1675 lb.  The airplane gained vertical, cruise and top speeds as compared to the -27 blades.  So much was the change that we had to re-rig the airplane for the higher cruise speed.  The cost is the same as the -27 so this is a better value.  This is the standard prop we use on the model 12.
The MTV9-260-29 on an M14PF pulled 1810lb on our test rig.  This gain is from the increased diameter and the added power of the PF engine.

Contact Kevin Kimball for further details.