My opinion on strap pin location shouldn't count for much, as I'm not sure I have one.
On my CS-356, it's at the neck heel which doesn't affect the neck/end balance negatively... but... it does make for a slight tendency for the top edge to roll forward -- it can move in two dimensions instead of one, gimbaling from that center neck heel point depending on where/how your belly hits the back, if you see what I'm saying. This admittedly slight tendency got exaggerated a bit when I intalled Dunlop Dual Design Straploks -- the extra 1/4" or so space between the back and the strap made the guitar a bit more floppy. Even so... I'm used to it now, and it doesn't bother me as it might someone else.
I've heard of folks moving 33X center/heel pins to the horn, and even though it seems like that would feel more "solid" as the guitar hangs, I wonder what the different shoulder to pin strap angle would do to overall balance. Hard to say on an unbuilt guitar!
I'd put the input jack on the rim though -- unless you use those L-shaped curly cords.
Not that there's anything wrong with that.