I know this is a old thread. But my the first JD was a 316 that I bought new around 1990. It was around 5,000 bucks and did terrible with dandelion stems. I mowed a couple of cemetery's and it was a nightmare. The mower I owned before was a Lowes brand mower that I gave under two grand for but mowed the stems three times better. Well I traded the 316 for a 455 which mowed flawlessly. Have also owned a 757, a F-620 and just bought a John Deere 318 with 50" deck. Most modern commercial decks are raised up about a1/2 inch in front which does two things. It does not push over the stems so much which in turn allows more air to be pulled up through the front. I will be modifying my deck in a couple of weeks to minimize poor mow quality. I tried some tall grass the other day and all it did was push it over. So I know this will be needed. If any body wants, I will post my results.