Although I have not yet fired my newly acquired Remington 870 Police (used), I did a quick comparison with my Winchester Defender SG, both 18.5". I noticed the 870P was significantly heavier, which was no suprise considering the receiver was steel, and the blued steel bolt was a solid chunk of steel. The Winchester (wood-stocked version) was lighter, and therefore handier, but not by much.
The mag spring on the Remington was very stiff. Is this normal for the Remington or its Police models? I had a harder time loading shells into the Remington's mag tube than with the Winchester. In either case, the 870's spring makes for very positive feeding.
Overall, I like the 870P a lot. I would take up either one in a home defense situation.