Sell towers for bookshelves?

Elevick, are you referring to my current speakers as far as decoupling goes? They actually have NHT's spike kit installed, allowing each speaker to touch the floor at the tips of four rather sharp spikes only. Still, I think that I would have less low end without the low 8" drivers and the large cabinet of a tower. Though again, that is only part of the reason I would purchase different speakers, the main reason being an increase in fidelity. I would also consider towers with just tweeters and midranges, though i figure I could get more for my money with bookshelves, as I am willing to sacrifice some dynamic range on the low end. I think the proacs are along the lines of what I may be looking for.

Almost forgot, I don't really have much of a price range because I haven't though about this too much yet, but I would probably look to spend up to $600 or $700.

Quick question, how do the older B&W Matrix 804s compare to my NHTs? (With my current amplification)

Thanks for the feedback so far. I'm just sort of feeling around as I'm curious as to how much I would have to spend for a significant upgrade in sound quality in the speaker department.
Meiwan, yes I do believe that the towers may have too much botom end (due to their 8" woofers) in a smaller place, which is part of the reason I was thinking about bookshelves. I will not replace the towers until I can afford something of significantly higher quality, however. So you are saying that for the increase I'm looking for I would be looking to spend around $1,000? or more? Thanks for this help.

And as far as other advantages over the towers I have read that of bookshelves and towers of the same price, bookshelves will generally be of higher quality. I am looking for more detail in my music now, and am willing to sacrifice low end (especially if I cannot play music as loud at my new place) so I figure bookshelves would be something to try.