By "these speakers" I assume you mean the BMRs? I worked with speaker placement with both speakers extensively. Both do exactly what you would expect and are similar in overall bass energy.
See this post. BUT, this is HIGHLY dependent on the modes in your particular room. (My room is basically a cube, which is terrible for acoustics.) If you have digital room correction (DRC) or parametric EQ (PEQ) available, the issue is largely moot.
I locate my speakers very close to the front wall, generally speaking, because that pushes the speaker boundary interference (SBIR) frequency higher, where it is easier to treat with broadband absorption behind the speakers. Doing this also moves that null well out of kick drum impact range. I use DRC in every room to knock the bass peaks down.
You have to move speakers VERY far away from the front wall to eliminate SBIR. At 3' from the front wall, the SBIR frequency is 93Hz, for example.
I do not believe I commented on dialog in this thread. I did evaluate the BMRs for stereo movie and television duty in my other review, and I found them equal to the task to my Revel F206s. That is to say they handled the job perfectly well. I imagine they are also equal to the R3s in this respect.
The difference in horizontal dispersion is the difference between 120 degrees (R3) and 160 degrees (BMR). The R3 casts a narrower, deeper soundstage. The BMR casts a wider, more enveloping soundstage. Which you like is a matter of personal preference. Neither has much, if any, impact on intelligibility of dialog.
You may be thinking of this post in another thread--an opinion with which I do not happen to agree given that I have first-hand experience with both:
So im looking to put together a home theater and somebody recommend me the philharmonic Bmr , i look into it and the speakers looks fantastic and all the good reviews. I'm in........ But now i meet a person who works at bestbuy and told me to buy the kef r3 instead with his discount I'm talking...
www.audiosciencereview.com
[I edited this post to correct an false recollection I had about bass energy between the two speakers.]