Anyone Successfully Go from Floor Standers to Bookshelf Monitors w/ Subs?

My system is in a Large Living room which opens to dining room & Kitchen. I figure about 6k cu ft. I have Silverline Sonata speakers now with subs. Unfortunately I did not build my addition when I should have 10-15 yrs ago. Now I'm not really up to the task. Too old & wore out. So I'd love to make the LR a prettier room for my wife. One thing we talked about was the large speakers, and possibly using Watkins Gen 4 monitors. But as good as they sound, I am concerned about the ability to fill the room, or at least my listening area. As I understand, it is about moving air. I cannot see how a 6.5 & 1 inch speaker can move as much as a 10, 7, 3 & 1 inch. So I am quite concerned about that. Right now, the system sounds very pleasing to both of us. We don't want to take a backward step but can live with a sideways step if it is more visually pleasing.

Has anyone made this kind of a step from floor standers to monitors, both with subs, in a large room, with success? Or am I thinking correctly about the small speakers inability to move the proper amount of air for the room size? Thanks for your help.

OH, FWIW, The addition may not be completely out of the picture. But it depends on whether I can get one of my previous sub contractors to do a large part of it. 
Yes, but & this is a big “but”- was second system, upgraded to used Harbeth 30 M, took a lot of time dialing in subs from “not there”, almost there, too much there, way too much there” & back, wouldn’t have worked for main system.
good luck!
Here also.  Went with nice bookshelf speakers as monitors to record my records to computer then record to cd. 
  Was great, went back to my BIC v-630’s  for recording. Much better!

 Still love my bookshelf’s!,! 
Switched from floor standers to Focal Sopra No1. Very happy. But these are anything but "bookshelf" speakers - the speakers and the Focal stands together weight around 100 lbs. I do have a sub, but most of the time I feel I could easily go without one in a mid-size room.
I've just taken that route. Had large OBs and changed to ProAc Tablette with two large sub-woofers. This is filling a 15' x 32' x 8' room that opens with an extension of 16' X 10' . 
It fills the room quite a bit. But only when the subs are on. The small bookshelf speakers will not cut it all by themselves. 
The speakers are fed via a 20 watts class A tube amp. The subs are 15" with 250 watts amps each. One per channel. Works for me. 
From Mag 1.7i and others to Proac D2 stand mounts and WOW- Also have a pair of James Loudspeaker Subs for when you want a little more bass-=-= Those Proac bookshelf speakers are special-=-