So here's Nathan Drake with an M9/92fs:http://www.flickr.com/photos/bogey175/9146652564/
Made using a hand drill on a tactical sidearm.
Not much, but it did lead to a self-revelation: I think that when the detail of trigger guards helps characterize the shape of the gun as a whole (especially with hand guns) I prefer to make it hollow. I'm aware that most LEGO guns are solid and, obviously, minifigs don't have trigger fingers, but it can be an important detail for me apparently.
And I do believe in such a thing as too much detail (slide releases, selector switches, often actual triggers, etc.) but I felt it complimented the overall shape, which was already closer than other vendors, to that of the real thing. Thrash, who I believe was the one who modeled the tactical sidearm, has a great eye for the overall form of accessories and translating that into the minifig world. And lots of his and BF's guns look just fine with the guard filled in. I just don't feel like the LEGO style always demands a filled in trigger guard.
And yes, this is all artistic taste and interpretation. And yes, this is a long post for one little drilled hole. But I'm curious as to how others feel about minifig trigger guards.