Ok, I also have been a pro 4.1 owner for about a year now -- I recently recommended my friend buy the logitech z-560s, the price is unbeatable, anyways .. after setting them up at his place and warming them up, did a few tests.
Gaming (both of our systems have Audigy cards ya ya i know not true 24bit but sound decent enough)
The logitechs are excellent, the bass isn't quite as tight as the klipsch i found, but for gaming the difference is not noticeable, they boomed when they needed to boom, and the mids are very strong, I was really impressed with these speakers at first.
Music
Played some diff stuff, alternative, dance/trance, classical(brought some test cds along), this is where I really missed my klipsch's, I love the highs and bass the klipsch's give compared to the logitech's, i found the mids strong - but highs and bass not up to par with what I was used to getting from my klipsch speakers, also at high volumes they started to sound even worse.
DVD Movies
Ok, first off that m3d switch in gaming and music I personally dislike it, in dvds i just dind't care for it, it seemed to add some interesting surround effects in dvd playback, personal choice though, anyways again, same results, boomy bass, strong mid, yadda yadda you've heard it all before.
Anyways, I'm not just saying this because I own a set of klipsch 4.1's, but they are better than the logitech 560s, BUT the price of the logitech's really makes them attractive, foe half the price, you are getting 3/4 the quality in comparission, if I was getting a new speaker system today -- i would go logitech 560 OR Klipsch 5.1 or Videologic (if you got the cash) The price of the Klipsch 4.1's need to be dropped to compete with the new speakers coming out, great speaks tho, definetly not plannin to part with mine anytime soon