I am a diehard Proac Response devote. My principal speakers for the last 20 years has been Response 3 until last November. But I always coveted Response 3.5. For the last 5 years, I have also owned a pair of 2.5 that I swapped in and out. Much better and more expansive bass compared to their bigger, older brothers (3) but not quite the midrange clarity and effortless extension. Coupled with an ER1 subwoofer, the 3.0s edged out the 2.5s... Of course at twice the list price, they really ought to bury them, but they don't ($6500+$2500 compared to $4500)! I also had a CC1 center channel, recently replaced with CC2. I have just sold the CC1, 2.5 and 3.0 when I was fortunate enough to find a pair of Response 5.0. Sonic nirvana!!! Subwoofer is now only used for home theater. I prefer the older response line to the newer D's with the ribbon tweeter. I would not agree that one is better, it is a personal preference. I willingly substitute a bit of high end speed and extension for what sounds more natural and musical to me.
With all of this as groundwork, I would not hesitate in recommending a pair of 2.5s for a small or medium sized listening room. They are just magical and for the $1500 +/-... a sonic bargain! If your room is big and your system top end, spring for 3.5, 4 or 5 (if you can find them. Keep in mind that all 3 of these require room around the speakers and must be away from the back wall several feet.
My current system is Linn LP12, Aurender N100, Classe Sigma SSP, Classe Amp 5 with MIT analog cabling and Nordost USB. Previously, I had a Krell KSP 7B with Audible Illusions S-120 and EAD/Wadia 12 CD. My next purchase will be top of the line Classe monoblocks as these speakers deserve them! Good luck in your journey.