I don't know anything about the bikes you're considering, but I really wonder how much faster you would be on one vs the other, especially over a relatively short distance.
I do know that being in pain can slow you down, especially over a long distance.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles