I came of a 450 yz and I can tell you a few pros and cons
Pros
Instant power, no more (less) downshifting to stay in the power
Many fewer stalls,
Much easier to start initially and doesn't flood out if you lay it over
Lighter feel, less tiring to race
It's a better woods bike in my opinion
Cons
Noticeably more engine vibs. Especially on a 300 ( all brands are this way on the 300)
Less stable feeling, in the rocky creek beds you'll notice more deflection off rocks
Most 2t bikes don't feel as good on hill climbs, kinda hard to stay in the ruts
In my opinion, your average weekend warrior/trail rider is more comfortable on a 4t, they are smoother, and build confidence quickly. Thats why the industry transioned to 4t. 2t bikes are tradionally more radical on power delivery, but modern bikes are more tame. If you want to try and race, or really push yourself to get faster, a 2t is less tiring and more, seat of the pants fun. If you are really used to 4t's then the transition to a 2t will be annoying. But nothing is more fun to me than a properly jetted/running smoker in the fast flowie single track. Hope that helps.