First, you should always use XP style scaling. Second, third party applications just don't scale, while native windows UI scales just fine. Most applications will work fine with XP style scaling, what you want to avoid is non XP style scaling which looks like garbage.
None of this is a problem in Windows 8.1, everything will scale properly - they changed the DPI scaling methodology in 8.1 to adjust in 2.0 increments instead of 1.6.
Also i'm not sure why this ATIV 9 is being compared to the rMBP - the only comparable aspect is the screen, in terms of hardware it is inferior to even the macbook air, much less the rMBP which is a considerably more powerful machine.