If you must tinker with your Glock, why don't you ask the professional doing the conversion what they would recommend. You are going to have a professional do the work are you not? To do otherwise is folly.
A friend of mine tried a Chandler Arms unit in her G19. With the weapon empty, cocked and the magazine removed, the slide would move slightly out of battery as she would press the trigger to the rear. It exhibited this same tendency when loaded, with or without a magazine in place. As this is the only time I have encountered the Chandler Arms unit, and never tried this unit in another Glock, I can not say for certain that this is the rule. It
was, however, enough to prevent me from buying one when I bought my own G19.