Used JMLab Chorus will blow them both out of the water.

for $200? I've heard both the Pioneer SP-BS41-LR  and the Infinity Primus P163, and the P163 are definitely better sounding to my ears than the Pioneers. They dig a little deeper into the bass and are easier to drive. The drivers in the Infinity Primus series are very good, but placed in so-so cabinets and with a so-so crossover. They really benefit from reinforcement of the cabinets, new acoustic stuffing and replacement of crossover components. With mods they approach the performance of afore mentioned JMLab Chorus.

http://www.stereophile.com/content/pioneer-sp-bs41-lr-loudspeaker

http://www.stereophile.com/standloudspeakers/1007inf/

if those pioneer speakers are still available...

they were discontinued, as far as i know.

IMO, the best speakers you can get for that price are the Polk R300 speakers. (newegg has them for only $80 each right now!)

I think they are considerably better than the ones you mentioned.

The Pioneer speakers would be a particularly bad choice due to their low sensitivity.

Update time!  I scored on craigslist and got a pair of Paradigm Monitor 7s AND a Denon DRA-685 receiver for $300.  I'm going to be selling the receiver and buying a (heavily upgraded) Yamaha MX-600U amp and a Carver CT-17 preamp though.  

I'm loving these Paradigm's though.  Aural bliss.

The Chorus I was speaking of would be the 7XX or 8XX small or large standmount.  I lived with 706 for about 6 years and sold them for just under 200.00.  They are really some of the finest speakers I've heard, up to some much more expensive JM Labs.  They are cheap because they are plentiful.  They are plentiful because tons of people in the world heard them right next to very expensive standmounts and said, 450.00?  I'LL TAKE THEM!

They were in a few ways, imaging, natural timbre, etc. better than my much more expensive used (and especially new!) Matrix 3 Series 2's.  I used them with a 80 watt-ish Arcam A80, Hafler DH200, and my GTA SE-40 and no matter what you use, they cleary delineate the differences, but always sing.  They are as good as nearly anything at distinguishing instruments and vocal timbres, is that Joni Mitchell singing at a Piano, or one of the talentless lounge singers audiophiles seem to love singing "Both Sides Now" in front of a Yamaha keyboard.  That kind of thing,

Anyway.  You can do better than either of the speakers mentioned.

Good luck in your search.