As i recall the 400 is $1700 unruddered so your looking at around $2050 .
I was in the same boat as you mate , had my heart dead set on the 400 and that was going to be my next kayak . Then i heard about the 4.3 and decided to wait and see . Im glad i did to .
I was supposed to have a test paddle of the 4.3 but got back from a fishing trip to late so missed out .
I can still try it out but dont have to .
I know 2 mates who both paddle the 4.7 and they both say the 4.3 is very very fast and quicker to get moving than the 4.7 .
For me the 4.3 has some quality features and in my opinion is one of the best kayak fishing platforms going around .
Ill be paddling one sooner rather than later .
As the other guys have said if these are the 2 yaks you have narrowed it down to then go for a paddle in both before you make your mind up .