The difference is still not even that 1 DEF. +1 Upgrade =/= +1 DEF
The actual DEF difference between a +7 Muff and +8 Hood is a pathetic 0.34 DEF.
The difference between +10 Muff and a +10 Hood is 1 DEF.
If you're not absolutely whoring DEF then a +8 Hood will be pretty much just as good as a +7 Muff, and a lot cheaper to make usually.