I too own one of these and it is a beautiful watch, but keeps pretty lousy time, losing more than 20 seconds/day. Only my inexpensive Orient, Seagulls, and an old SKX lose as much time. I think it is likely a 'quirk' of the movement - maybe the curvature of the movement architecture is more susceptible to positional variation?
If you can live with the relative poor performance (I only wear it for a single day at a time every now and then, so the -20s/day isn't a huge issue for me), given its scarcity (only 100 examples of each dial were made) and the fact it has an in-house movement (and the thinnest big date movement in existence at that), the price is reasonable.