I had several Sunstars with the 60" decks, and I was told that the outer blade chops the grass up better, and also, I did remove the baffle between the second and third blade, install a different belt since you bypass a pulley, and then use a standard blade. Results??? Well, the deck uses less hp, but leaves a streak sometimes between the second and third blade. Less suction to pull the grass up from the right front tire, so I changed the deck back.
I don't know if my experience with the 48" decks (where the blades all turn in one direction) is relevent to your question, but I always had a problem with grass collecting just above the back end of the bar that runs under the outlet opening. It would neatly deposit big clumps of grass at regular intervals all over the lawn. :duh: Very frustrating. It was really bad with older blades (probably less lift) and bad enough with new. I finally took the bar off; That solved the clump problem, but left the deck somewhat weaker. Now that I have 60" decks, that problem is gone. :bannana:
The reason Simplicity went to the odd lh blade was to reduce streaking in that area and lift grass pushed down by the left front tire. The very original Sunstars with a 60" deck did not have the odd blade on them. Not clear on my memeory but only a year or two were built with all the same blades.