Bricasti M1 vs DCS Debussy

The MDx upgrade in my system was huge improvement. Every aspect was improved in my M1. Most startling change was image improvement. Depth, width, and height is now just fantastic.  Nothing about the MDx upgrade was subtle. My M1 had the 1.3(?) firmware.  

The MDx upgrade in my M3 brought the same results you described.  Very worthwhile upgrade.  I swapped out the board myself.  20 minute job.

I also received MDx update on my M1 SE this monday.  Initial impression is as @hifipf described that the image improves on various dimensions like depth, width.  Not so much on height because of my system and room limitation.  The firmware version now shows MDX 1.02 on my unit.  I played around the filter for a bit and liked the Minimum4 the best so far.  But it really is system dependent from the rest of your equipment.  All others like Minimum0 as well.  The unit still needs break in and I will probably need to experiment other filter settings along the way.