Hello,
I listened to the Proac Response 2.5 and Coincident Partial and Super Eclipse II.
Both hooked to Rogue Tube Mono-blocks. Pre-amps deferred (We tried Rogue, Canary, Joule-Electra, Shanling Solid State, etc).
These speakers represent two different house sounds:
Eril's description of Proac is bang on in my mind.
Very sweet and warm mid-range.
Slightly rolled off highs and not the tightest bass around (some tweaking can be done with the sponge that blocks the port and a powerful solid state will control it better but its basic character remains).
Probably typical British sound (easy on the ears, warm but slightly soft and not the fastest and most resolving).
The Coincident sounded much faster, more dynamic, extended on both ends, clearer, more resolving but more than anything: open and ambient (lots of air) at the expense of less mid range lushness/body and sweetness.
The Coincident is more tube friendly to say more efficient.
Which is better?
Personal preference and your room and gear of course.
Probably if both speakers' fortes could have been integrated in one set of speakers they would have been the cat's meow...
To my personal taste, I would want some happy medium and if forced to live with one or the other I would probably do the following:
Proac- I would try to match it with a 5751 tube based pre-amp which is sparkly, has a forward mid-range and very extended on both top and bottom, like a Joule-Electra LA-100 Mk III and a Bi-Polar based powerful Solid State amp (Bryston 4B, 7B Simaudio W5).
Coincident - I would go to tube only front end, preferably 300B (that is what they were designed to work with) to try to get more mid-range body while retaining the airiness and clarity.
To summarize:
They're both good speakers. Define your preferences and have a listen to both.