Speaker size and soundstage

In my many years of audio, I have found that in a domestic living environment, the speaker/room interface is a total crapshoot.  I'm talking about rooms where you have limited placement options, seating options and furniture-moving options.  I have never found a correlation between speaker size and how they worked in my room.  Some did and some didn't. But you should experiment within the parameters you have.  Moving a speaker a few inches closer or further from the back wall can have a big effect on the sound.  

Electronics also play a part. I found that my Revel speakers had a wider sounstage with an Arcam amp, than with a comparable Cambridge Audio amp. 

Overall size of the soundstage, specificity/precision of the soundstage, dimensionality of the soundstage, scale of the soundstage are, in my experience, distinct and dependent on multiple variables including electronics, isolation, noise, room, speakers, etc.  The only one I’ve found to correlate with size of the speakers/drivers is soundstage scale (eg. musicians and instruments sounding larger or smaller).

Baffle size and cubic inches make all the difference when it comes to dynamic full range sound in a large room and you will especially hear it when you get a true full size full range speaker that has a baffle three times the height and twice the width of the woofer you will not believe the foundation and depth of sound when you hear a big speaker loaf along in even a very large room. Small narrow baffle speakers with small drivers will not do this or any semblance of this type of sound at all in any size room.

There are a couple of items for comment.  

First is room acoustics.  It's probably the most critical component in soundstage.  A well-tuned room is both the starting point and the finishing effort in any listening environment from the basement cave to the symphony hall.  Without the room, it will not be possible to set up a fully satisfying system.

A very easy and inexpensive room tuning solution is using 5" artificial ficus trees available at most home decor stores.  "At Home" stores sell them for $40 each.  I ended up with about 15 scattered around the room, mostly behind and next to the speakers.  They act as diffusers and work great.  It's probably the cheapest and most effective room tweak available.

Next is optimizing speaker setup.  Much as been written about speaker set up.  Most is total crep.  But do try to keep the speakers away from the back wall and the side walls.  Place an artificial ficus between the side wall and the speaker a little forward of the speaker to break up the sound heading for the side wall.  You don't want those side wall echoes.  

What is a "bigger speaker?" What is a "smaller speaker?"  

The Dynaudio Contour 30 is a VERY good speaker.  I haven't heard the Tekton.    

Soundstage and imaging can be somewhat controlled with the speaker setup and room acoustics.  Artificial ficus trees are the 

I have gotten spectacular soundstage and imaging using a speaker with a single 5" driver in a mass-loaded transmission line enclosure.  It was a nearfield setup in a larger room that the OP describes.  Wonderful system, punchy, tight and fun, but a little lacking in macro dynamic range and sub-80hz bass.  And nearfield listening helps to remove room interaction.

I get spectacular soundstage and imaging with my current 3.5 way four driver speakers with 12" and 10" woofers, 6" mid and 1" tweeter drivers in the same large room --- obviously NOT a nearfield listening setup.  But it does provide a very wide range of dynamics and sub-40hz bass at maybe 20 times or more the size of the 5" MLTL system.  

But the MOST satisfying listening comes ONLY in a room that is properly acoustically tuned.