Security Cert on that site is expired... weird.
Carbon railed saddle is by Astute and sadly discontinued. I find it extremely comfy and purchased several of these while cheap on clearance.
Want one now... ebay & $500+ so I'm not changing any time soon.
The "odd mount" is not a function of the saddle, but an accessory mount that came as part of the seat post saddle clamp.
The mount is a standard GoPro mount and also used for some tail lights.
I believe this addition will add ~3oz to the bike (including the carbon bottle cage) and removal/replacement in under 20 seconds.
So my proposed setup makes a lot of sense to me.
I really wanted the MO-BO but I have found what I hope is a second best option.
If it turns out to be compatible I'll follow up soon.
Barry