I tested different blades today. Here's what I came up with:
1) I could not tell a difference in the cut quality of balanced 40 degree vs balanced 30 degree. Not even in the sound of the engine. (Briggs Pro 8.75 with heavy flywheel.)
2) After 30 minutes of sticks and light gravel the 40 degree blade was still in good shape. The 30 degree blade showed signs of wear and tear and needs to be re sharpened. However, still no apparent cut quality difference...just noticeable vibration on the 30 degree blade now that is out of balance.
The new blade IS out of balance but still no quality in performance.
-New blades need balanced not sharpened.
-40 degree edge lasts longer and cuts just fine on then average lawn.
-30 degree should cut better in thick stuff and is better on spindles and/or engine but won't out last a 40 degree edge.
let me know if you guys want pics with a more in depth review of my redneck blade experiment.