Thanks for the help guys. I made a purchase, I'll report back how I like it just incase anyone else is considering a similar upgrade. I ended up buying:
MartinLogan Motion 40's for L/R
MartinLogan Motion 30 for Center
I'll be running these with my Velodyne Optium 10 and Polk FXi A4's for surround. If I'm happy with the ML's I may pick up the Motion 4, 15 or FX for surrounds. Setting up a single Motion 15 or 30 for surround back could work nicely, and use the FX for surround L/R. I never understood the need to have more speakers in the back then you do up front. 6.1 seems to be the ideal setup, or perhaps 8.1 if you used side speakers. 7.1 and 9.1 just seems odd to me.
I have a Zvox 555 Soundbar that absolutely kills my Polk CSi5 on deep vocals. I'm guessing part of the reason is it has a built in powered sub. That made the DT 8060-HD or 8080-HD very tempting as a center, I bet the built in sub really makes for nice vocals from deep voiced actors. If I'm not happy with the ML setup I may try the 8080ST and 8080-HD combo from DT. Too bad the 8080STs look like cheap construction, could use a touch of class.
LG 55EC9300 OLED
2x LG 55EA8800 OLED
Sony 65XBR850A LED LCD 4K
Samsung UN46D8000 LED LCD
Yamaha RX-A3000 + Oppo BDP-103
Martin Logan Motion 40/30/FX + Rhythmic 15" FV15HP