First impressions then!
Length fits the same as my GR3's. Width is narrower. In general walk-around-the-house mode, this was fine: they just felt a little snug, but not in a bad way. First half hour on court, and I had a fair bit of discomfort. The narrow bit isn't where I'd expect at all - it's on the outside of the shoe where my arch is. I had to loosen the laces to stop this pinch, and was ok after that. In contrast, the toebox was pretty roomy. Usually if a shoe is too narrow for me, that's where I feel it.
The insoles are probably the thickest I've ever seen out of the box. They seemed to offer decent support, so I tried them in 'stock' form tonight. They're pretty good, but I had a small grumble from my shins near the end so I'll try switching them out for my Superfeet next time. I could only fit the blue ones in the GR3's - I'm hoping that the green might fit in these.
I need more time with the shoe, but in general it felt very responsive: much closer to the GR2 than GR3.
So to answer my own question about the sizing: length was true to size, width was narrower than the GR3's (or the GR2's for that matter). Going up a size would have been no good for me, as the extra length would have been too much. For those of us with somewhat wide feet, there is at least a break-in period: the upper is pretty flexible though, so hopefully this won't be too much of a problem for me. If you have particularly wide feet, you're probably better looking elsewhere.
My String Journey: http://tt.tennis-warehouse.com/showthread.php?t=362403