Hmmmmmmmmmm. I just read what I believe was your first post here at Audioholics. You have a modest sized room, do not need hi volume, and want accuracy. My ramblings:
Your choice of center speaker will be the most important, and even more so for you imo. Stay away from the typical horizontal mtm speaker if at all possible. Accuracy in HT is not too difficult imo, EXCEPT for the human voice. Who is to say that an alien spaceship coming out of the ground in War of the Worlds sounds inaccurate on a system?
Floorstanders will require more power, because of the lower x-over point or just pure lack of. For 99.9% of the speakers out there, its the low frequencies that are harder to drive. Whats nice about the .1 subwoofer is that it usually comes with its own amp as well in the purchase.
That being said, a hi-quality pair of towers will provide better bass than a pair of hi-quality bookshelves + crappy sub. I know, I've experienced it first hand. Not even close (depending on units compared of course). Otoh, the lfe channel is its OWN channel, but I still strongly believe what I say in this paragraph.
The 605 might be fine if volumes are indeed low/moderate, in your modest space, with modest distances from speakers. Could be quite fine indeed. Does that unit have pre-amp outputs in the case that you ever did go crazy and/or moved to a much larger space?
for extra thoughts on bookshelves vs floorstanders, I offered my own opinion in post #25:
http://forums.audioholics.com/forums/showthread.php?t=34792&page=3
Now, many people say they think they can get better performance from hi-quality bookshelves + hi-quality sub, lets say in a music rig. Because the best placement for bass rarely coincides with the speaker locations. Otoh, in a typical room, I find that there really isn't so many sub placement options either, if looks matter at all. For argument's sake, I think that the success of such a setup can matter very much at the x-over point chosen, and the ability to "dial" it in.
Honestly, for your needs, you probably will be happy either way, be it bkshelves or floors. Floors will have similar height and similar footprints, but maybe they just might look bulkier. Eye of the beholder... then again maybe they could be the best looking pieces of furniture in the room
The x towers look like they might be very good lookers. Another line to check out are the PSB towers, you should be able to find T45's for a very similar price.