have you got any links to the cars? Are the 3ltrs all in the lower tax bracket?
If you didn't know the 2ltrs are flat fours and the 3ltrs are flat 6's - which are train driven.
I've got a 2.0R legacy Saloon. I think its about 160/5 bhp so its nothing to write home about, but it's good enough for me. Using vpower I can get around 34/35 mpg with a mixture of town and motorway driving, which is about 400 miles per tank. It was on 87k when i bought it, its now on 105k. I've only had to replace the dics/pads and the clutch and the dual mass flywheel. - which i converted to a single mass flywheel. - the single mass was considerably cheaper and the DMF's have a tendency to sequel, so I opted for a single mass flywheel and clutch. I also need a new exhaust, as the Y piece has a hole in it. - Which is a common issue with legacy's, so it's definitely checking out when you go and view one. A Stainless steel exhaust is probably going to cost me about 400-500.
If i was buying another, I'd probably go for the 3.0R with the 50k on the clock. The Spec B will probably have blistein suspension, but personally I'd rather have the lower mileage. The 3ltr engines are solid and pull really good! Ask Dave, he's got a 3ltr outback.