I own a PS90, I really like the rifle but I wouldnt want it as my main rifle. The 5.7x28 honestly is a low power round. For 200 meters, the bullet will get there and is relatively flat with regards to trajectory, but the 40 grain bullet just does not carry much energy with it as factory rounds are only going about 2375 fps.. For close range (like 50 meters or less), its ok. It appears to slowly be gaining poopularity with the AR57 uppers being out for a while now. If I recall correctly, another company is coming out with 2 guns in 5.7x28 in the near future, so maybe, just maybe more companies will start making 5.7 than just FN.
My best advice, if this is for a primary SD/HD rifle, get an FS2000. 5.56 chamber, 1:7 twist chrome lined bore, STANAG mags, truely ambidexterous and shorter length with its 17.5" barrel than my issue M4 is with its stock collapsed.