@doni I just think the Blade are the best speaker I have ever heard. There are aspeakers with a little better drivers out there (for ex. Yamaha NS5000). However, the way the Blades project the soundstage in unsurpased with every other speaker I have heard. I have gone to a a few shows and have heard a lot of gear. There are also incredible audio stores in Southern California. So I am not basing my comment from limited experience.
BTW - the Yamaha NS5000 is also an incredible 'bookshelf" speaker that would likely be great in your large space. You can get a home demo of them from 2 online sellers. I expect to get the NS5000 over the Blade because the side firing Blades are a bit more difficult to place in my living room. I have a local NS5000 dealer.
BTW2 - I expect the KEF Blades to be upgraded soon with the META technology that came with the most recent LS50's.