I did a 1" FBA on a sz20. The pattern doesn't have side seams, it has side panels instead so I ended up cutting them in half, doing a standard princess seam FBA on the front half and then taped it back together.
The fabric is a ponte knit that I got on the Melbourne sewing trip. I really wish I got more because it is a great fabric and hasn't pilled like the cheap pontes I get from Lincraft (even though it was actually cheaper!)
I added a button to the front instead of having the tie belt that came with the pattern. Its ended up a little off centre because the fronts are wide to allow for the tie belt so I had to put the button across too far. After I took these pics it annoyed me enough that I skimmed some off the side seams and moved the button across but am too lazy to take new photos, sorry!
I'm really happy with how it turned out. I have a real thing for jackets but just never wear them so I like how this looks more like a jacket but has the comfort and ease of wear that a cardigan has.