Welcome.
I can't answer your questions becuase there are two more strings than I am used to. However to the extent that the B4 and F4 are contemporary and comparable I will note three things. (If I am thinking of the wrong guitar as being comparable, then Never Mind
)
1) It is wonderful having the built in electronics and in my case I am happy with the way the acoustic sound is amplified.
2) As an acoustic it can hold its own with one D-25, in a small room but otherwise there is a reason the electronics are there.
3) The prices for B4-Es are falling right now. The ones that are selling on eBay seem to be going in the $400-$500 range. So my uninformed opinion would be that $438 is a good and fair price (depending upon condition) but it is not such a bargain that fellow LTGers will be fighting each other to snap it up if you don't get it.
But what do I know?