Creek 5350SE: is it a noticeable increase over the 4330SE?

Hi folks, 

I currently have a Creek 4330SE, Naim CD3.5 and Vandersteen 2c speakers w/ DH Labs Q-10's speaker cable and Air Matrix interconnects. 

I'm thinking of upgrading 4330SE to a 5350SE and was wondering if it is a beneficial move? Now, I love the sound of my system and the 4330SE powers the vandys plenty. My system is in a second bedroom and is approx 12x14. The 4330SE is 50wpc and the 5350SE is 85wpc. Generally speaking, when I'm casually listening to music, the volume on the 4330SE is usually in the 9-10 o'clock range on the dial. If I'm working aound the house and want to hear it from the hallway or the office, I have the volume at 11-12 o'clock and it doesn't break a sweat. 

The stereophile review favors it very well and even the author commented that is was consistently better than his 4240SE, but added the 4240SE was still very good. I'm wondering what benefits the 5350SE will have over the 4330SE? Will there be more punch and dynamics? Fuller, more detailed mids? Has anyone owned both that could pass on some user comments? 

Another thing I think about is useful volume range. Is using a 5350SE in a 12x14 room overkill? The article did indicate the 5350 is a passive preamp (as is the 4330) so perhaps the linear volume range is similar?