I am 60 and have been riding for 45 years. I have a 2010 KLX250S that I bought this last summer for $3700 and it was like new with <200 miles on it. It had a skid plate and Acerbis Rally Pro handguards. I love most everything but freeway riding. I have gotten 70 mpg, but I have also gotten 50 on the freeway with headwinds. The 2.0 g tank must be supplemented with a Kolpin or Rotopax can if you live in a rural area like I do. I am also going to purchase a gen 2 KLR for the more highway riding and use the KLX for the 1000s of miles of 2 track dirt roads here in NV.
The term "dualsport" by it's very nature implies compromise and there isn't any way around it. What side of the compromise do you really want to be on? I ride regularly with friends on KLRs. The real word economy between the two is surprisingly close. If you start playing with the jetting, your economy will go down. I live at +5000 foot and ride much higher than that and I get by with stock jetting very well.
I am in the process of buying an 09 KLR to supplement my KLX.
You, alone, have to decide on what end of the compromise you want to be on. In the end, if you're doing mostly pavement, the KLR will be pretty close on economy and it will have a much better range.

 

alright, I am planning on my compromise still. when I accomplish that, I will give you a call bert and we can hit the hills since we are neighbors.