Posting this again in case anyone wants it and hoping to trigger the math challenged lurkers some more.
fill out a blank sheet like the picture and paste the following into cell K12:
=((1/(1-(MAX(IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6),IF(F12"",IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6)+((1-IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6))*IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6)),IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6)),(IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6)+((1-IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6))*IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,G12/(6-(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))))*IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6))))+((1-MAX(IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6),IF(F12"",IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6)+((1-IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6))*IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6)),IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6)),(IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6)+((1-IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6))*IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,G12/(6-(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))))*IF(IF(OR(D12+I12>6,D12=""),"",D12+I12)="",0,(7-IF(OR(D12+I12>6,D12=""),"",D12+I12))/6)))))*IF(E12="",0,(7-E12)/6))))*IF(H12="",1,2))*C12)/(A12/B12)
now you can analyze the relative durability of your units.