It's made life simpler over the long haul to have most things cross-compatible between bikes. Flat tire and it's time to ride? Swap in a spare wheel. Forgot to fix the flat when that one came off the bike? Now it's time for the spare bike. But that's over a dozen years.

Are you going to keep both bikes that long, or will you want a new bike in a couple years?

Without knowing the specifics of this year's groups, I might be thinking about mechanical disc brakes on the "rain" bike so I could switch wheels, and only need one kind of brake pad spares.