I carry them on 5 of my EDC pistols. Best bet is run down to the gun shop and try the display gun with CT's mounted. I would say 1/8" on the left, right and rear...if that.
"Does it become as thick as a g23 or g30?"
Not sure what you mean. I have them on my 17's, 19C, 26. and my 29. The 29 is the larger frame. I have big hands so even with them on my guns the grips still feel small to me!
Most of the large retailers have displays to try before you buy. If you have small hands it might be a problem. But my daughter and granddaughter love them too! (they are both small).