What types of bags will you be using? Rack top, or panniers?
I bought a generic version from my LBS in hopes of using it on Brevets - it was too short once mounted to make things work comfortably. I also found the with the load hanging out there it made the bike odd for climbing. Felt different than with a regular rack that mounts down to the drop outs.
I switched out to a Tubus Fly
and used a touring pannier on one side, loaded lightly. Worked well, but I didn't like the unbalalnced load for brevets.
Plans for this fall are to do some light touring / long brevet style rides - staying with friends or credit carding it - I'll use the Fly with 2 panniers and a light load. Should work great.
If you are choosing the seatpost rack due to mounting issues, Tubus makes some great QR adapters for their racks. You can probably use them with most other racks as well.
So long. Been nice knowing you BF.... to all the friends I've made here and in real life... its been great. But this place needs an enema.