It sounds like your question is whether to buy the S1.4 New from the dealer, or the Special 25 used off of Audiogon.
Go with the dealer. The S1.4s are excellent sounding, and unless you have complete top notch gear and room, they will not be your weakest link. The S25s are better, yes, with bigger dynamic capabilities, and a smoother top end due to the better tweeter. They are both ultimately similar sounding, though, and both completely awesome and incredibly dynamic (and full bass) for their size.
However.... and I don't mean to rain on any parades... but don't get Dynaudios with a 12x9 room. You will never by happy. Even though these Dynaudios are monitors, they need big rooms, even bigger than many floorstanders.
I had the S1.4s in a 13 x 15 room, and even this room was too small for them. No matter what I did with room treatments, the bass was peaky, and I couldn't drive enough current through them to get them to open up.
I would look for a small sealed box (or front ported) for that size room. For bass, with that sized room the placement flexibility of a small subwoofer would be best.