Monitor Audio GR20 or JM Lab 906

Beginning a new set up in the family room(17x25). It will be used for ht and 2 channel. Due to Sound Advice discounting the MA GR20 they are the same price as the JM Lab. Will drive them with either Rotel,ADCOM,B&K or NAD.
I listen to mostly jazz and pogressive rock. A center channel and sub will be added later.

Any help is appreciated.
FWIW, I owned both the MA GR10 and the JMLab 906 at different times. The GR20 I heard in the store only. For my money, I preferred the 906; for its resolution of low level detail and higher frequencies and overall balance. However, my room is smaller than yours, and the GR20 will have substantially more bottom end. Some may prefer its weight in the lower mids and bass. Then again, if you intend to add a sub anyway...
Thanks for the input. The weight in the lower mids of the GR20 for HT is exactly why I liked the speaker(not to mention the 30% price reduction).

What if I dropped down a level to the Cobalt 816s?

Will a sub reproduce the low mids or will it be too low to accurately blend in these frequencies?

I'd be more enthused about recommending the Electra 926, which might be available at a good price, now that the 927 Be is out there. As you may know, the 926 got some pretty good reviews awhile back as a full range option.

I had the Cobalt 816 home for an audition before choosing the Electra 906. I did prefer the Cobalt to its rough equivalent in the MA line, the Silver S9i which I owned at the time. Recently, I upgraded to the 927 Be. I find the bass and mids more satisfying in the 3 way version of the Electra line, but, going by memory, the GR20s had more bass weight. I can't speak to sub integration; it's not something I've tried with my better speakers.
Good luck!
The B&K and the GR20s would be a fantastic choice! Never heard the JM but the GR20s are a sweet speaker with great bass control as long as you use an adequate amp. I myself am a progressive rock freak. Let me tell you Geddy Lee's bass sure sounds ultra sweet on the GR20s. I love mine! Good luck!