So, I'm a little late to the party. But, for the sake of anyone who actually uses the [admittedly difficult to use] search function before they start a new thread, or any lurkers, here's my take.
I have their standard dot as the front sight on my sp101 - which didn't have a rear to begin with - and it's rather spectacular. I can pick up the sights fast, and speed (DA) shooting silhouettes @ 10 yards my shots are all within COM, so I don't have any complaints there.
For more - and I'm talking in relative terms here - precision shooting it took some getting used to, but I can hit COM @25yds, which is all I really expect/need/can do with a snub anyway.
So, to summarize, I love the standard dot, but it's already quite large, so I'm not sure how useful their "big dot" would be on a handgun.
I'm also not sure that I'd want to give up the rear on a gun where it was an option.
si vis pacem para bellum