Well I reckon ride both and think about what you do and what you may do in the future
The weight difference is 10 kilos which isnt earth shattering IMO. The 400 is a really nice bike that gets big wraps.
Owning a two stroke has benefits as does the 4 stroke. If you are going to turn in over in a few years the expense of rebuilding the 4 stroke wont be an issue. Fitting a piston in the two stroke around 100 hrs or whatever isnt a big deal either.
Ride them for yourself, I know your up the coast but Sutto’s have a ride day down here soon where you could ride them back to back. For me the 2 stroke is fun for a bit but they arent my cup of tea, either are some of the new 4 strokes, although mid next year I plan on buying another bike
I would look at a 400 but only KTM make a 400 enduro at this stage (is that right? :blink: ) and I wont be owning one of them 
Good luck to you, it isnt easy spending your hard earned but rewarding when you get it right 
TB