You rock! And so does your LHT!
I've had mine over a year now. And it's my go-to bike! I kind of get the whole one-bike-to-do-anything, now.
I never found one that fit this in my life. The LHT is it though. If I went back in time, (although I dearly love my 520 and it's an amazing bike) the LHT would be my first and only choice.
I don't regret buying the other, it's nice to have. I ride it plenty. Such as when the LHT is down for regular maintenance. I get pretty fussy about maintaining it. But, yeah. 
As far as mileage, I have no idea how many miles I do or how fast I go. I think keeping track of it for me, would suck some fun out of it.
Just because, I'd probably go slower than I'd like. LOL.
"Things look different from the seat of a bike carrying a sleeping bag with a cold beer tucked inside." ~Jim Malusa
2009 Trek 520-Brooks B-17 Special in Antique Brown
2010 Surly Long Haul Trucker-Brooks B-17 Standard in Black
1983 Fuji Espree Single Speed-Brooks B17 British Racing Green