My modular approach is for backpacking; when speaking of my BOB, I just use Transformers instead.

...Meaning that I have a Columbia system jacket that can be a rain/wind shell, a fleece jacket, or a winter coat depending how it is assembled. The nylon pants in my BOB can also be shorts, but in the winter they are the layer that goes over the thermal underwear. I keep all this packed year-round so that I can handle a cool night in the summer as well as the unexpected warm January day (70's, very rarely). So I shift strategy to multi-purpose items rather than swapping modules. This and Space Saver bags (zip them shut then roll the air out the valve) make it work.