Can anyone compare a FN Herstal PS90 to a Tikka T3, or Ruger Target Mini-14, for long range varmit hunting?

After much talk of trying to hunt prarie dogs, and with only owning deer rifles or shotguns, I bought my father a Tikka T3 in .223 with a 8-16x40 scope, and now I'm looking to buy myself a gun to use for similar shots, but I also want something with semi-auto large-magazine capabilities. The Ruger Target Mini-14 has a target trigger and harmonic stabilizer on the barrel end (looks like a supressor, awesome!) and there are 90-round mags available for this gun. At $800 this gun is affordable so long as it delivers its promise of target accuracy at 200 yards. However, I also am interested in the civilian model PS90, chambered in 5.7x28mm, and wondered if anyone knew how well it could perform for long-range accuracy when well scoped? The Tikka .223 gives penny-sized shot groups at 100yards, so how would the Target-14 or PS90 perform when equipped with similar scopes? Most real hunting shots would be at 200+ yards, so does the 5.7x28mm round fall way too short ballistically to the .223?