Considering a POSSIBLE replacement for speakers. Opinions?

Find some used dynaudios - I'm currently in love with my special 40's.

As someone else wrote, the Monitor Audio Silver 300's are the new model version of yours, if you like Monitor Audio Speakers. I have a pair of Silver 500's and I really like them .They are the same speakers but with 8" woofers instead of 6". For some people the 500's might have too much bass and they prefer the 300's.

Call Coincident Speaker Technology . He has introductory floor model speakers at a reasonable price . My friend bought them and they sound good . It's not one of the ones pictured on the website , all of which are more expensive .

I'm in similar boat as OP.  I have MA Silver 6's and have really enjoyed them again since i've optimized much of my system around them.  I have enjoyed listening to other speakers but am wondering how much I'd need to spend to get a quantum leap in performance.  
@stereoisomer  I think making a leap across family to MA gold and the ribbon tweeter might be the biggest bang for the buck leap you can make.  Never mind the finishes on the gold line are simply gorgeous.  I'm not convinced moves within the silver line, or moves to a different manufacturer at a similar price point, would buy you a ton but will monitor this thread for real world experiences.   Good luck! 

@bdp24 , I would not recommend the LFT-8B even though it is superior to most box speakers it is horribly inefficient and has a predictably weak mid bass as it switches from being a line source to a point source. You can not switch gears like that with a loudspeaker. It is also the weakness most Martin Logan speakers have. The volume of line source loudspeakers falls off much slower than point source speakers so as you move away from such loudspeakers you lose the bass. Imaging also fractures. For those of us using line source loudspeakers this problem has significant implications for subwoofer use. This is a problem I wrestled with for years. You have to create a line source subwoofer system capable of reaching up to the frequency that the woofer panel starts switching to point source. In this instance that is just too high for any subwoofer system. With Maggie 3.7i's you are talking about 250 Hz 
which is doable but not the way I do it as I cross at 120 Hz. You would need to make two subwoofer towers as high as your ceiling. I would use 10" subwoofers spaced two feet apart. An 8 foot ceiling would require 4 drivers each side.  Making corner enclosures would be a novel approach.