About that rumor the G-29 is being phased out: It's just that, a rumor! Started toward the end of 2006; there wasn't any truth to it then; and, there isn't any truth to it now, either.
Top Glock and Budd's, both, have G-29's for sale; and the factory continues to produce them. The reason I prefer the G-21 is because - with simple barrel, guide rod, and spring changes - I have the option of using a G-21 as a dual caliber 45 acp/45 Super pistol. In 45 Super my G-21 will rival or even exceed many 10mm loads. (And with heavier bullets than the 10mm is able to handle, too!)