If your muzzle or sights are moving at the end of the trigger stroke you don't have the proper trigger reach on the pistol and an adjustment in your grip or finger placement on the trigger would be ideal. As for rolling your primary shooting hands thumb outbound, away from the slide over your support hand thumb, this is not too much of an issue and is often a common fix for the thumbs forward grip where the shooters thumbs may be interfering with the controls on the pistol. This is common for an aggressive and high thumbs forward grip on say a Sig Sauer or for the Glock with the extended slide stop. I will note that what I am describing is NOT the same thing as a "crossed" or "tucked" thumb grip that is common on a revolver grip.
I will also mention that there are indeed better techniques out there that will produce better results depending on your type or style of shooting. Just because one technique might work better for you than another, the old "Use what works for you" may not always be the best. Proper training or instruction can help remedy much, shy of an actual physical limitation.
Surf can correct me, but I believe this is what he is talking about if anyone was confused:
Standard “high on the frame” “thumbs forward” or, insert tacticool grip name here _____________ :
Notice the thumb and hands are right along and touching the frame, making plenty of skin to frame contact here. The basic jist is I'm going to get as high up on the slide to help reduce some of the recoil and lever action that the gun has.
Thumb slightly outbound, just off Sig Controls.
This is kind of the same concept of the standard grip, but in order for me to have consistent function of the controls I need to get my thumb off of them.
Thumb further outbound off controls and onto joint of back thumb.
Same as above but slightly exaggerated.
Little more "oldskool" locking thumbs on each other.
