Tower Speakers and Room Size

Hello,

I have been considering a speaker upgrade for my modest rig:
Rega Mira 3, Onkyo DX-7555, Infinity Beta 40 speakers with decent IC's and speaker wire.

My listening room is 16.5' by 13.5' with 8.5' ceilings. My guess is this would qualify as a small room?

I recently listened to the Monitor Audio RS6 through the Rega Mira 3 and Rega Saturn CDP. As you probably know, the MA RS6 has gotten rave reviews for the price range. My impression was that yes they have detail -- they had nice timbral detail and air, but something in the treble bothered me. It was as if the treble was almost too crisp sounding, which makes me wonder if they can get fatiguing.

Then I listened to the PSB Imagine T through the same rig. Slightly more recessed in the treble (as compared to the RS6), but with noticeably great imaging. I did feel that the bass was a bit vague compared to the RS6, since I thought bass was a strong point of the RS6. Nonetheless, I believe I found the Imagine T more pleasant to listen to.

The dealer says that they will have the PSB Synchrony series in stock for demo in the fall. My question is will the Synchrony One be too much speaker in my 13.5' by 16.5' room?

Also, neither speaker really blew me away. Sure, I shouldn't expect to be blown away in this price range, but perhaps I need to take another step up in terms of price to really hear a significant improvement.

In terms of feedback, what are your experiences with speaker size vs. room size? I do want towers, but if matching their size to my room size is important, I want to know that so I can narrow my search. Thoughts?