I have a grass flap on a Ferris ZT. Use it ALL THE TIME, to mitigate spraying clippings where I don’t want them to go. In the fall I use it to rough mulch leaves keeping it closed. The pieces are not as small as my neighbor who has a Ferris ZT with a mulch kit. After several weeks, my yard looks like his thought because of natural rotting. What the grass flap also allows is for controlled side blowing. I can cut and discharge away from edges. Then go back over the discharge with a closed flap. When the mower starts to bog, opening the flap clears it up.
Not so much with the neighbor’s closed mulching kit. I shake my head when I see him stopping to clear under the deck. The drawback to the grass flap is that it will leave windrows when shut. Not a huge issue and nothing that can’t be resolved with a pass back over and a secondary discharge cut.
Spring grass and rapid growth should also be considered. Wet thick grass will torture a closed mulch kit. So you either have to do it in several cut depths, several mows, or super slow to avoid clumping and engine struggling. Not an issue with the option to open or close the grass flap.
You do sacrifice small/fine clippings with the grass flap because it does not have mulching blades. To me, the versatility overrides the desire to see less clippings. (Which again dry up or rot quickly depending on the season)
Yes, the neighbor has already said he wished he would not have gone the mulch kit route because it only works really well when the grass is dry and relatively short to start with.
I’d like to say it’s efficiency and not laziness…. I really enjoy back blowing the edges of the driveway back into the grass as a clean up after mowing instead of having to dismount and get the hand blower. I can with the grass flap, I couldn’t with the mulch kit.