Dynaudio Contour S5.4 or Confidence C2

I have always been a great fan of the Dynaudio speakers, went from Contour 1.8Mkii to Contour 3.3. I am thinking to upgrade again to S5.4, however confidence C2 is also within my consideration. Any advice on this? Has anyone compared the 2 and can comment on whether the improvement justifies the price difference (about $2k for used pairs).
I am using sometimes Sonic Frontiers Power 3 monoblocks and sometimes McIntosh 501 pair to drive the speakers.
I owned the Contour 5.4's for about four years, and recently sold them to pursue another diection. They are incredible speakers, I won't belabor the point with audiophile jargon, but I'm sure you would be very happy with them. I have not heard the C-2's, but I have to think that the 5.4's are the sweet spot in the Dynaudio line-up.

Best of luck,
I personally prefer the confidence line. I own the c1's and demoed the C2's in my home. If I could afford the upgrade I would do it. The confidence series is more open - detailed with a better soundstage (both in width and depth) in my opinion. I think the 5.4's are a little more forward (especially in the mid's) but also has a bit more 'punchy' bass in the low end (not bad mind you but more like the C4's).Your room will also play a big factor.

That's my opinion and would suggest if possible to demo both side by side so you can form your own opinion. Both are fantastic speakers in their price points.
From what I've seen in the classifieds, used 5.4's have been selling for around $5K... and used C2's are only another $1,000 or so. Go with the C2's now and save up for C4's!
neither- save up for C4s if you want the floorstander. why buy a 2.5 way speaker.
Thanks for the great response so far. My concern with the C4 is placement. My little audio nirvana is really quite little, measuring only 13'x15' with relatively low ceiling. The C4 really will dwarf everything in the room with its height reaching almost 6'. Is that a valid concern?
I have my C4's in a well treated 15' x 21' room. I don't think a 13' x 15' room is large enough to let the C4's breath, as they really need to be pulled away from surrounding walls to sound their best. If you want to stay with Dynaudio I'd look at C2's or C1's with a nice subwoofer. Both of your amps would work fine either way.
Pdreher is right regarding the C4's. You will never really hear the full potential of the C4's with your room. Have you demoed the C1's with a sub? You may be surprised.
I agree with the room being to small for those C-4's. I never owned them, but after interacting with other C4 users, they can be difficult to place for bass and the more breathing room, the better. They are stellar Dynaudio speakers. If you like the Confidence line, I'd suggest as others have the C1's or C'2s. You may even want to explore the Sapphires, but they are more costly. The Sapphires do work well in a smaller room. Your amps are quite fine.
13' x 15' room?

Honestly, I am really surprised that you are getting good results with the 3.3. Do you not have major bass problems in your room?

I had S1.4s in a 14 x 16 foot room, and they were great, but completely overpowered the room in the bass.
with 13' x 15', the C1 is your ideal speaker. it has bass down in the low 30s for you. try them out, several pairs on a'gon. if not enough, go further up the pipeline.

but C4s are definitely out of the question for you---refer to stereophile review for more information.
I had the C2s for over 4 years and loved them, but they too need room to breath, and show off their great soundstage.
I heard the C1's this past weekend at the AKFest show and thought they, with the rest of the system, was excellent; one of my two favorite rooms. Clearly a great match for the smaller room; I was told they tried a larger version, I didn't catch which model, and the C1 easily performed better as it was a better match for the room.
I forgot to mention I have a pair of ASC tube traps in the corners of the room behind the speakers, and I have the 3.3 toed in. I used a sound meter and a test tone CD that sweeps the frequencies to do a simple analysis of the acoustic response of the room, and selected the tube traps accordingly to target at the frequency range. I know this might not be too scientific, but the bass is quite well controlled that way and the overall effect is to my liking. I am leaning towards the C2 based on the response so far. C1 with subs might be too complicated.
"I am leaning towards the C2 based on the response so far."

If you are happy with the bass response of the 3.3, the C2 could work.

I would avoid the S5.4 with your room size, for sure. Too much bass output.

Is an in home audition a possibility?
Again, thanks for the valuable responses. The bass response of the 3.3 do tighten up tremendously and go deeper with better resolution when paired with high current amps. Coincidently, this is why I fell for the SACD format (relatively to redbook) when played on my APL 3910, SACD just gives you that extra extension and resolution IMHO. I am hoping the C2 bass response would benefit from that too. Unfortunately, I cannot arrange for any home audition. I am located in the San Jose / SF bay area.
btw, note Dyns need 3' or so from the back walls to sound best.

good luck in your auditioning.