I know Deena at acend told you the 200s will be too small {when I called for 340's she tried to talk me into towers for $1500 more lol}, but here is where I am coming from...
You need...
an innexpensive
bookshelf speaker
no rear porting
smallish size
that dont mind being fired straight forward and are not too position sensitive
To me the 200 fits all of these, the only problem is that your room is large... But heres the thing, I dont know how many guys in here tried the 200's but I own 3 pairs {well 2 just sold one} and they are very capable, sure would larger speakers sound better, yes.. but they dont fit every other aspect you need... The 200s will get the job done, will you have rock concerts in your living room no, will hey easily get you to 90+db yes... And the only thing that the 200s lack compared to the 170s is the bass, where you are going to have a sub...
They have a 30 day trial period if you dont like them return them just buy your front 3 or 1 pair...
Sometimes you have to make comprimises, I understand why you dont want towers, and I cant blame you my kids are 11 and 13 now so I dont have to worry about them running behind my speakers pulling the wire and getting a 60lb speaker on their head.
Try them out, I cant see any other option and I think you will be impressed...