All great comments.
I think for larger windows, the rectangle modules would perhaps get you more coverage for the buck (than nodes) ... and its 3 5050 LED(s) per instead of one ... so thats either a good thing or not. I think the rectangular form factor is more conducive to simple frame mounting, whereas if your willing to to more sophisticated frame mounting (drill holes and deal with alignment issues) ... then nodes would work ... but would be a level of difficulty higher and 1/3 the LED(s).
I know having multiple windows on the same SSC might not make sense, unless they close (wiring distances would factor) ... but in LSP 2.0 you can set up each of the channel ranges as a different controller (same SSC, different channel range) ... and even leave out null (interconnecting/repeater) nodes/modules as needed ... so you still get to program them as independent objects that way and collapse controller, etc. Again, in LSP, maybe not other software.