When you look at decks for mowing wet grass there is alot to look at. You have to make sure that the discharge opening is large enough to disperse the clippings properly to avoid clumping. The more baffles under the deck, the worse the deck will perform in wet conditions. "Square" corners in decks will trap grass and cause clumping, decks that have smooth corners will cause less clumping. You will also want to make sure that the mower that is coupled with the deck has the power to move through wet or thick growth.
Here's some pictures of the scag velocity, JD 7-iron and exmark triton (hope this works).....
'07 Chevy 2500HD
2010 John Deere Z925A 54" MOD
2011 John Deere Quik Trak 647A
John Deere walkbehind