Nothing.
A few of the "boycott boys" will chime in and tell you what a POS they are. But they are not.
The action makes a different sound because of the different parts, but that's no big deal.
The lock just sits there, out of the way, doing nothing to hinder the performance of the weapon.
Personally, I don't care for the HiViz sights. But sight preferences vary greatly from person to person. I always like black on black.