I've tried mulch kits on both an Exmark Turf Tracer HP 48 inch with a 17 HP Kawi and a Lazer Z HP 52 inch with a 23 Kawi. Both have Tri-Vantage decks. I found that both mowers gave a great cut with the mulching kit and the wavy mulcher blades. They didn't stripe nearly as well as with high lifts discharging, but the lawns looked very nice.
The problem for me was in the spring and early summer when the grass is growing like crazy and is lush and juicey. I had to slow way way down at times and avoid cutting when it was wet. I didn't get all that much visible clumping...it's more of a mush...but I'd get the mush on my tires that would peel off randomly across the lawn as I mowed.
The biggest problem was when picking up a new account that was a bit overgrown to the point it was too long to mulch without choking the mower and making a mess, but I couldn't discharge and bag it because my mulch kit was on.
In the end I decided that mulching just slowed me down too much and wasn't worth it, at least in the spring. What did work fairly well, and I really don't know why I don't do it anymore, was to put the mulch kit on my Turf Tracer after the heavy spring growth spurt ended and discharge with the Lazer. That way I could mulch my smaller lawns and cut in around the beds and edges with the Tracer and not make a mess on the bigger ones before hopping on the Lazer to knock out the larger areas.
I can't see having a mulch kit on if you only have one mower, not in the spring at least.