Its not just that, its also that the voltage of the sunpower/solara panels are generally much higher. Even though they are only "slightly smaller", they start outputting useful current
at a higher voltage earlier in the day and much latter into the evening. So, using your high voltage solar
panel up north is much like using your solar panel down south. This also means you need smaller wires, which weigh less, are easier to install, and so forth.
All this translates to real improvements in the number of Ah a day they can be expected to provide, which means you need even less space.
If cost is the only factor than, yes, you can't beat a Kyocera panel; but for us the 4" per panel size savings is the difference between having 280 watts on our bimini
or 420. Thats a major difference which in turn means I can get rid of our generator
1.5% to 24% efficiency is a major improvement - a 6% relative improvement over the 22.5% cells and 41% better relative to 17% efficiency Kyocera cells.