Here are the pics. The difference between the two crowns are summed up nicely by this visual.
As you can see, the Sinn is signed, while the Seiko isn't. In fact, the crown on the Seiko appears to be tarnished. Dude. Seriously. WTF? What's up with that? The Sinn has interesting knurled, grooves cut into it, while the Seiko is boooring. The Sinn is easy to grasp, the Seiko slips while unscrewing. The feel of the Sinn while screwing the crown back down is comforting; the feel of the Seiko is unsettling. Awful, horrible feel! Plus, I always have to actually turn the watch over to tell if it is fully screwed in and seated against the watch case. I'm starting to get the hang of it, but something about the Seiko just feels bad. Very, very bad.
On the plus side, though it is likely more a property of the movements than anything else, the Seiko winds "like butta".
Once you have the crown unscrewed, it is a true pleasure to wind. This has got to be one of the nicer winding watches in the world. I'm pretty sure it is better than my Rolex movement's winding feel. Curiously, it reminds me somewhat of the feel of Matt.wu's 2892-based Kobold Seal, but is tons nicer than the 2892-based Omega 2254 SMP. 
This beautiful winding experience is negated, however by the associated trauma of having to go through the process of screwing the crown back down when finished. This Seiko crown sucks! * Also, be careful not to cross thread your Seiko, as due to the unique design of this case, a repair will be nigh the cost of a replacement watch. (or so the Internet lore says; no personal experience or facts to back this up)
