I'll chime in here because I have a Tri-Cycler mulcher on my 38" LT133 mower. I have felt that "it was worth it" to the extent of buying a replacement air deflector after the original broke off. Last year I mowed without that deflector, and still got fairly good mulching action, using the JD mulching blades and outlet cover alone.
The mulching is superb so long as you are cutting fairly frequently. I mow at 3", and it does nicely if what you are cutting off the grass is no more than 1-2 inches. More than that, and it will leave windrows, and if you are plowing into 10-12 inches of grass, it will choke up and leave large uncut stripes. If I need to cut tall and rank grass growth, my 318 50" with medium lift blades and an open chute will charge through grass and leave a clean cut where the mulcher gets overwhelmed.
It is clear to me that much of the mulching action comes from the blade shape. These have a significant bend upward on the leading edge inside of the main cutting area that reverses the air flow. The lift wings at the ends of the blades are lowered somewhat from medium-high lift, so the overall effect is that of a low-lift blade.
My primary reason for mulching is to return nutrients to the soil. Wyoming conditions are
"dry, dusty, alkaline" and even with good irrigation, keeping the topsoil in condition, as well as acidifying it, is a primary concern.
Can't comment on Gator blades as I have never used them. Nor have I really considered putting a plate over the discharge of the 50" mower. While I get some windrowing when I mow the pasture every 2 weeks, I watch the grass pour out of the discharge, and it seems to scatter perfectly well.
Where the mulcher really shines is in falling leaf season. I may have to make two passes, but the leaf residue just vanishes.
Hank