I started shooting double-action with my 986 S&W because I figured it was how I'd shoot it if I needed to quickly. I almost never shoot it single-action, because I want to get used to the trigger. However, I have to admit the few times I shoot it single-action, my groups improve.
I started shooting double-action, partly out of the challenge of doing it. That and my usual carry piece is a Kahr K9 semi-auto that is very DAO-like (though it is striker fired). I can shoot my K9 well, but it is certainly easier for me to fire my Springfield XD with a custom very single-action like trigger, and I can group better with it. However, the same goes for a full-sized CZ 75 with once again a better trigger than a Kahr.
If double-action is working well for you, shoot it. I shoot what is fun to shoot, my groups be damned. I bought an LCR in 9mm for the challenge of shooting a DAO snub-nosed revolver, and I love shooting it now. The LCR has a really excellent DA trigger. I say shooting DA will only improve your trigger control. Just do it lots. I bet whenever you switch back to SA, your groups will tighten from all the practice in DA.