Good question...I'd like to know as I too am in the market for a trunk. Also, is that trunk easy to attach/remove depending on riding preference and how is the overall quality of that trunk (latch, seal, ease of opening/closing...things like that)?
I'm happy with my Corbin trunk so far, it's built well, but some have reported issues with the finish. Mine has some slight cracking on the underside near the mount point. The latch takes some getting used to, and occasionally it will lock itself on bumpy roads, and I just about freaked out on my last trip as my key was in a liner pocket inside the trunk...then I remembered I had stashed the spare in my wife's riding jacket. And I think it would be super simple to pick it if needed. A huge plus for me is that you can open the lid fully and it wont knock a helmet off the rear seat. For some reason my wife and I have a problem with that, and we've (I won't say specifically who!) trashed two helmets with my previous GIVI trunk. It opens and closes easy, but I always check it, because if the latch is slightly turned, it won't positively catch. A very minor thing. The seal seems pretty good, I've been in downpours and driving rain, without a drop getting in, but it does have a channel (like a car trunk) that catches water if the bike is on it's side stand. I just blow it out. It's pretty easy to install and remove--take the rack off, set it on, and install the 4 bolts. A second person is helpful, but I can easily do it by myself. I'd hate to drop the thing though.
Oh, get used to the fact that when you make stops, for some reason everyone comes over and leans on it, places their maps on it, huddles around it, etc. It's that big.