Juggler,
In my experience, the Glock Model 20 is an exceptional pistol. Not only is it extremely light weight (approx. 30 oz.), but it is quite powerful as well. Along with these attributes, it also has proved itself to be one of the most accurate Glocks. It sometimes amazes me what groups I can cut freehand on targets with minimal effort.
As to its light weight qualities, my main purpose for this pistol is hiking in the Rocky Mountains. When I go for a 15 mile hike up and down thousands of feet of elevation, weight matters. For this, I leave the .44 mag. at home.
As some have pointed out, it is a bit more expensive to shoot than lesser calibers, but they are LESSER calibers.
For a package so accurate, reliable, light-weight, and powerful, what more can you ask.
As to ammunition, if you desire to realize the full potential of the round, I would recommend your friend purchase ammunition from any of the following manufacturers: Double Tap (doubletapammo.com), Cor-Bon, Buffalo Bore, or the 175 gr. Winchester Silvertip load (this is what I currently carry).
Hope this helps. -- cox3497