It could be that a 155 saddle is too wide. The 143mm width might work better with either saddle. It could also be that a different shape would be better -- I think someone here has found the Specialized Oura to be most comfortable.
Another thing to consider is the shorts. For example, if they are old, is the chamois wearing out? Or is it bunching up or causing chafing for another reason? Or are the shorts too big?
- Gray Trek Madone 4.7 road bike, mystery crack in top tube repaired by Calfee, Bontrager Affinity RXL saddle
- Red Trek 6000 mountain bike, Bontrager Evoke WSD saddle
Gone but not forgotten:
- Silver Trek 2000 road bike
- Two awesome and worn out Juliana saddles