My understanding of the benefits are:

1) Reduced noise and vibration (permits prop. synch to actually function as intended)
2) Shorter ground roll
3) 30 or 40 lbs lighter

Downsides (from reading posts):

1) Potential cruise perf. DECREASE
2) Susceptible to FOD (particularly rear prop) - though I understand the blades can be built back up rather than being 'dressed out'
3) OH's need to go to factory (which could occur with some frequency..., see #2)
4) No front boots (though I heard you can get boots for the front)
5) Not T337G-P STC'd (yet?)

The reason I was looking looking at the MT's was because in my 337 AC search one of the birds would require new props (front and rear), and if I was replacing why not get an upgrade (if the benefits outweigh the downside).

Any first hand experience here?