Compared to the Legacy and PSB, Im more experienced with ProAc. I have always been a ProAc fan. Had been using the Studio 140s for a while and listened to many of their models ranging from the Studio, Reference and Response series admittedly Im sold on to D28 till date.
Now coming to your point (as well as the other recommendations above) I would like to know your exact need. How big is your listening area? Are you looking for a stand mount or floor standing model? In most cases these differ a lot in presentation regardless of the price. Since you have mentioned some fine floor standing models, let me assume that you are looking for one.
Personally I like floor standing ones for their grand presentation and full bodied sound. Now this at times comes at a cost of not being able to drain out the last bit of midrange refinement or the keenest top end but compared to the presentation and soundstage it gives, not to mention the iron grip bass I would go for a floor standing model any day.
Having said that, the plus point of opting for a stand mount/bookshelf model is that you are getting one of the best refined presentations in that price category. The mids will be glowing and highs will be sharp. All this might come at a slight cost of deep tight bass.
At the risk of making this sound as if its all about the bass, let me assure you that these are quite mature models and when we talk about bass here, its the tight bass with a punch that gives an impact you know it's right; not the boom box type flabby overbearing bass that many entry level floor standing models torture you with.
If you have the space, by all means try the Studio 140. It will not disappoint you at all. But if you plan to use it in a smaller room, may be the 140s will be an overkill. May be the excellent Tab Ref 8 Sig would be a better fit closely followed by the Res 1SC. Either ways, feed them with as good a signal you can, and these truthful speakers will do justice to your investment.
The intention of this post is solely based on my personal experience and not generalizing an idea or school of thought. Some like stand mounts and some prefer floor standing ones; end of the day if you are happy with what you hear - its some money spend right.
thanks for the feed back. like you said i am looking for floorstanders as i already have a pair of standmounts. i am also considering elac fs 208 a floorstanders. my power amp works between 4 and 8 ohms .the nominal impedance of elac is 4 ohms and is suitable for amps from 4 to 8 ohms which is o.k. but the minimum impedance of elac is 3.4 ohms at 190hz. will it effect my amp?