I own a pair of the 360's you can see my impression in the my HT link in my sig. I really like the speakers and would not hesitate to recommend the 160 or 360 to anyone (not the 162/362 as they are lower quality). The problem is the 160/360 are no longer in production but you can still find them used on ebay/craigslist an Harman is selling the 160 for $90 a piece direct from factory.
http://www.harmanaudio.com/search_browse/product_detail.asp?urlMaterialNumber=PRIMUS160BKS-Z&status=
I will have to disagree there. I find the cabinet to resonate quiet a bit and it fails the knuckle rap test pretty easily IMO. That being said I wouldn't expect any speaker in the price range to be braced much better as they are braced to the typical extent done by the average DYI builder from what I have read and seen inside the cab itself.
The speakers real secret lies in its drivers wide, reasonably linear, dispersion make for a great full sound that make the 360 more enjoyable than other speakers with more well braced speakers. (This is the reason the drivers are going to be used in my build).
For reference check out the measurements in this review:
http://www.stereophile.com/floorloudspeakers/605infinity/