I just drove over and grabbed the 3906 and put it on layaway until Friday. I'm darned glad that I did. It was the only police trade-in 3906 (Gwinnett County and Sherriff's Dept, in Georgia). When I asked for it (all of the LEO trade-ins are behind the counter) I was told that it was probably sold from when I saw it this past Saturday. It had gotten a lot of attention. But, it was still there with the single stack frame easy to spot. The gun is in very nice condition and just a little work will make it like new. I'll change the grips as they have a few dings at the butt, a common place for wear. The gun has the low mount night sights (pretty well depleted) with a blackened trigger, hammer and ambi safety. "Gwinnett Co. PD" is stamped on the right side of the frame. To me that just adds nicely to the gun as I live a very short distance to Gwinnett County. By way of trivia, Larry Flynt was shot right by the Gwinnett County Courthouse after his obscenity trial. Gwinnett County, well northeast of Atlanta, is also the home of the infamous Runaway Bride.
The gun feels darn good in the hand. I find my 5903 really comfortable as I have medium large hands, but the 3906 feels really good. I also like the heft and I think the gun may well be a real winner.
Again, thanks for the comments helping me to decide.