After much research and deliberation, I made the decision last Thursday to order the Sinn 556A.
The watch arrived at my office Friday morning before I did. As I was told by the gentleman from WatchBuys who called me Thursday afternoon, I removed only the plastic covering the crystal and set the watch at 11:00 a.m. Friday. I kept a (too) close eye on it through Sunday morning to make certain I wanted to keep it. I noticed that by Saturday morning, sitting face up, it had gained about 7 seconds. Nonetheless, I decided I liked it quite well and would be keeping it, so I removed the rest of the protective plastic and adjusted the bracelet to fit.
After wearing it through Sunday, I observed that the time was now 2+, and that has remained constant through the day and night, and is still +2. Quite satisfactory. I'm going to give my 21-year old DateJust a bit of a rest.