Of course, the preference is for high detail all the way to the edge. That's why people pay big bucks for top quality glass, right?
If that's the case, than perhaps the G1 isn't the body to be using with such glass.
That being said, I've found that for the photography I do, very rarely is the subject at the edge of a photograph, and any smearing in the prints that I do is essentially invisible.
In addition, I have a real affinity for vintage glass that heretofore was considered rather dodgy...the Summarits and Canon 50/1.2s and 0.95s of the world, etc. These lenses are by their very nature imperfect, that's what gives them their character. Having never owned any Leica ASPH glass, perhaps I just don't know what I'm missing, but perhaps I'm more willing to accept less than the ideal.
For example I'm currently playing with a Macro Switar H8RX, 36mm f/1.4. It's an amazing little lens, it's designed for 8mm but actually comes within an eyelash of covering the G1 sensor. It has some really interesting character! But it would probably not reach minimum performance of many photographers. I took this photo with it. Uncropped.