Having just attempted this myself on a friend's character (he's quitting the game), let me share my experience with this BCNM.
He had more than 200 seals, so that gave me 5 chances at this BCNM. Results? 2/5. Got a Mimic three times, died for all 3. You can't run out of the BC because the Mimic will Tractor you back in. Not sure about Warp scroll though.
Every fight that I won yielded 2 items and bout 2000 gil. So, at the end of the day, I got a Darksteel Ore, a Tamer's Ring, a Tracker's Ring, and an Astral Ring. Total earnings: 520k, but only because of the Astral.
Was it worth it? ...I don't think so.
Had there been enough time, I would've personally preferred to get a group together and attempt the Mandragora BCNM, but it was impossible since I only had a couple of hours to get things done. 200 seals would've easily gotten 3 million gil's worth of items, and would involve more skill rather than luck.
So, my advice is -- if you can get a group together to BCNM with you, then do it. This Treasure and Tribulation thing is pretty much a game of chance... and it's all good if you're lucky, but it's gonna be a little hard to swallow if you're not. Either way though -- good luck.