Upgrade from Vandy 2w to 2wq.

Can anyone tell me if the 'Q' function makes a real difference in the sound quality?
In one word: yes. I have owned both the 2W and the 2Wq, and the 2Wq is a meaningful improvement over the earlier version. I currently own a pair of 2Wq's and confidently recommend them to serious music listeners (but not for LFE in home theater). The Vandy 2Wq is one of the true unsung bargains in high end audio. If you decide to buy the 2Wq's, spend the extra money to buy the Model 5 crossovers, which are much better than the stock X-overs.
Thanks sdcampbell,
I already own the 2w's, but was considering the 2wq. that was for sale on Agon. It sold, but I am now considering upgrading to the Vandy 5's, instead.
The 2WQs will add the lows you may be seeking and the removal of the load on your amp will likely improve your high range.  That may actually be the best part!  I keep the "Q" level almost down to zero.  The higher you set it, the more boomy bass you get.  You can increase the sub volume separately from the Q level.  Get two (2) 2WQs!
Thanks jokerman, I really don't want any more bass, just more accurate.

Stringreen, I am looking at a pair of 5a's for sale. The seller is very accomodating (will meet me near my location). My only problem is whether they will fit in the space I have.
 I have 3a sigs currently and like the sound, but would think the 5a's would give me more flexiblity with placement, as well as give me more detail in sound. What do you think?