There are, as there always are, many "what if's" to consider that only the OP can answer. For me, the "what if's" clearly indicate purchase and use of a 6x12cm roll film back. But then, I'll only carry the light/small 6x12cm kit when I don't feel like carrying the 4x10in system... size/weight is the "major issue" "for me" for even having the smaller kit... and carrying several loaded sheet film holders is not part of the purpose of the small/light system. The 4x10in system I'll crop anywhere from 4x6 to 4x8 to 4x10.