I'll second the 7.62x25 Tok idea. That would be sweet--just as fun and far more functional. You could get some pretty good penetration from a 90 gr FMJ at those velocities, and unlike most available 5.7 ammo, bullets suitable for personal defense actually exist for the little Tok cartridge.
Until then, the PS90 seems interesting and is certainly fun, but it serves no legitimate purpose that I can tell that would justify its cost. If you have the money to spend on an expensive plinker with no real utility beyond paper and cans, more power to ya. I do not.
It's a shame too because with all the effort FN has put forth to provide civilian legal versions of their military rifles to the American market, I would love to be able to support them. Unfortunately, none of their products really appeal enough to me to drop that kind of money into them.
Maybe if the SCAR-H had made it to the market before I had my M1A...
Anyways, congrats on your new purchase. It makes your wheels go round, and that is all that matters.