I realize the cake's been already shared but I'd still like to share my subjective opinion.
AR1
WxW/Roper - Mab's (or perhaps he meant TTRR/Roper, which is also true) mentioned diffrences in map layout which I totally confirm. Recently I've impromoved in roper but I cannot see that affecting my WxW games at all.
Team17/Shopper - hehe
AR2
TTRR/Roper - same story as with wxw/roper
Shopper/WxW - Look very fair to me. With average roping it comes down to clever weapons usage and piling.
Having that said AR2 has 1 missplaced class and AR1 has two.
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Another nice option would be to play these playoffs BO3 and start with each player banning 1 class for this round, so that 3 classes would remain.