M6120, and all Shimano's performance braking products, features the newestI-Spec EVwhich is so much more awesome than all the past versions that I can't even be mad that it took them this long to get here. The side to side adjustment for the shifter is 14mm which is quite reasonable....
The X7 shifter has a more precise action than the X5 shifter and is also compatible with SRAM's MatchMaker system, which allows riders to use one clamp to secure shift levers and brakes. X7 is available with a 2x or 3x crankset. SRAM X9 Equivalent to Shimano SLX, X9 was the workhorse...
I suspect we'll be saying adieu to the SLX moniker as well, with Shimano paring down their lineup. In the current HG+ world, it's an unneeded middle point between Deore and XT, and Shimano has skipped it wholesale with LinkGlide. This gives a better idea of what a big shift is occ...