I'm currently measuring a 27.0" underbust, which I find to be quite surprising. The band on this bra stretches to 27.5" before there's wire distortion. I'm wearing this bra on the loosest hooks, but I feel like I could get away with the third hookset already due to slight sliding.
I think that the cups fit amazing. I feel like I've got a fantastic happy medium going on with it. My smaller side has a bit of gapping at the top of the lace, while my larger side is straining a bit, but isn't bulging. Pictures don't show the straining as much, but as I'm sitting here writing (and admiring my breasts), I can feel my larger side cutting into the lace a little bit. This affirms, to me at least, that I'm in between a KK/L cup. I think when I hit high tide, this bra is going to be too small. You'll also notice that on the side view on my larger side, not all of my tissue is encapsulated by the bra cup, but it's pretty close.
I'm pretty happy with the fit, albeit it's not perfect, but it's 10x better than my current 65J bras that are digging mercilessly basically everywhere.
Updated on Feb 15, 2019