[DW]

I was in similar situation recently, but trying to decide over the 500 or 300exc. Ended up going with the 2 banger.
If you are pretty good and can throw a bike around, what about a 500?
Only about 10kg heavier than the 2 stroke. Single cam so easier to repair than the 350 and more kms inbetween rebuilds.

 

[DW]

450 or 500 enduro, Can't go wrong I reckon.
Personally I was going to go with the 500 as I initially wanted a bike for a little more on road and dirt roads.
I never considered the 450 as they are basically the same weight as the 500 and tge 500 would have more punch, but the 450 is still going to go hard. Both good choices.

300tpi should be a good thing as well. I have a couple mates with them. Strangely enough one of them is a brilliant bike to ride where as the other is a pig. I am guessing they may have 2 different maps loaded into them.
I can't afford one and I was also going to wait a couple years until they had 3 or 4 models of the tpi out before I look at one.

 

[DW]

My 2012 300 doesn't vibrate that bad I reckon. Mine feels ok, but I suppose I have owned 360 and 500 - 2 bangers and fark me those things will vibe right up your body until your teeth chatter.
The one disadvantage of the 300 carby models on the road would be the tuning. Mine is set up brilliant for the dirt, but at constant throttle it leans out a fair bit and I get a little paranoid it's going to nip up.
The 300 tpi might be the best answer for that. Or obviously your 4 strokes.