I'm curious what led you to go that route as opposed to something with onboard mic inputs, or even getting an actual 2-channel preamp like a MixPre.
Good question. I own a MixPre-3, a pair of Sennheiser MKH 8040 and Audio-Technica BP4025. So why don't I just use them?
The Sony portables are what got me into recording, what is mainly quiet ambient and nature sounds for my own enjoyment. I have every PCM device since the D50, and will no doubt be buying the D10.
But it's the M10 and D100 that I use predominantly, and most of my favourite sounds have been pulled using the D100 and I always have it with me hidden in the car. The XLR-1 was bought here as a curiosity, but to me using it with the D100 sounds just as good as the MixPre-3. In fact I am thinking of selling the MixPre-3 and accepting that the use of external mics is occasional.
I'm curious to see how the D10 performs, but as I said above I bet it's no better with external mics than the M10/XLR-1 and certainly not the D100/XLR-1.
At the moment it's just a matter of convenience. I have the 8040's in ORTF together with the XLR-1 in one setup, I can just pick it up and go knowing that the batteries will be good, as will those in the D100 hidden in the car.