I've built two, a G19 and a G34 that I eventually put a G17 slide on. I made the G19 from inexpensive parts, with OEM internals, Bear Creek barrel, Swenson slide and a Burris FastFire III. The G34 was bought as a kit from 80PBuilder with their own parts, but needing a red dot due to my old eyes, I ended up installing a shorter G17 Bear Creek barrel, G17 Swenson slide, and a Vortex Venom.
Both shoot fine and feel good in the hand. They were fun projects, but they really do feel like what they are, homebuilt 'kit' guns. My Glock 17 MOS just feels like a fine European sports car while these have the look and feel of a 3rd gen Camaro. lol