Yes what I left out is that if you have 2 frames with the SAME nominal top tube length but DIFFERENT seat tube angles then the frame with the steeper seat tube angle has a LONGER Bottom bracket to head tube distance. I would say that the frame with the more relaxed seat tube angle but the same top tube length is actually a SMALLER frame with a shorter BB to HT distance. When you correct the steeper seat tube angle for KOPS then suddenly you have a longer effective top tube length.
Regards, Anthony