I wouldn't worry about hydraulic brake failure on the road. I imagine damage during a flight would be more common than anything else, but that can happen to any part on a bike. On my MTB I can use either brake for effective stopping and it's pretty easy on the hand compared to using cable-actuated brakes. On the road I don't brake nearly as much as I do on the MTB so of course the braking demands are different between each kind of riding. My next rando bike will likely have full shimano hydraulics.
I have the a600 pedals and they are pretty sweet. The non-spd side isn't even a proper flat and wouldn't be comfortable in flats for a long distance, but it's okay for going down to the corner store or something. I toured on them and it was nice if I needed to nip down to the store after arriving to my hotel. I think the a600 is designed around being light, hence the one side. I've always used one-sided spd pedals for randonneuring, there's not a lot of unclipping on most brevets I've done.
If ever end up doing a brevet in goathead country I'd like the option to run tubeless... and worst case with tubeless you can just put a tube in.