As others have said, the main issue with the G20 is the size and weight. This isn't the old west, or even 40 years ago where there was no choice but to carry something made entirely of metal if you wanted a handgun. This is the polymer generation. The G20 is only big and heavy when compared to it's counterparts today. Compared to something 40 years ago it's actually a decent size, relatively light for that size, and gobs of power.
With the right holster, and dressing around it, the G20 isn't all that much harder to conceal than any other full size handgun from what I've seen. Get a good holster and a very good belt. I also carry 2 magazines on the opposite hip to help balance out the weight a little bit.
It also depends a little where you live. Washington State allows open carry, so it doesn't really matter if I print or expose my firearm. I've never been asked about it or gotten funny looks while concealing it, because reality is that very few people care, and most of those could care less (from what I've seen, most people trying to spot concealed carriers are doing it as a game or exercise, and are usually carriers themselves)