The consumption issue has no rhythm or reason and it effects the 2.0 FB engine as well but it started with the 2.5. In March 2013, they implemented this ring surface treatment and it seems to make no difference from the people chiming in on NASIOC.com.
My 2.0i Impreza was built in November 2011 and I bought it in February 2012. Today I'm at 49,950 miles and have very minimal oil loss. I put in 5.5 quarts due to an oversized oil filter and that gets me a 1/2" inch over the full dot on the dipstick. After 5K miles, It's usually on or 1/8" inch over the full dot.
With Subaru's, the general consensus is not to baby the car during the break-in period yet the owners manual it tells you for the first 1,000 miles not to race the engine past 4K rpm, do not drive at one constant engine or vehicle speed for a long time, avoid rapid acceleration and avoid hard braking. Well, my car was a dealer trade and it was driven over 200 miles from Charleston, SC on I-26 & I-95. That's about a 3 hour drive at constant interstate speed and no problem to date.
If you want a 2015 Subaru, I say go for it. My earlier built FB engine doesn't have these updated rings and it's fine.