Seat post rack for a carbon road bike

[lkonya]

I am a new member of this forum, so my question might have been discussed already. I have a Scott Solace 40 carbon road bike (with carbon seat post) and would like to purchase a suitable seat post rack and rear bag. I am thinking about the Randonneur Seat Post Rack or the Topeak MTX Beam Rack. I wonder whether anybody has some experience with any of these two. Thanks for any help.