Played this (RC1) having been recommended it by some guy called Ribbiks. Phenomenal wad from start to end, bravo. I personally think this is easily cacoward worthy.
One thing i always admired in the original Sunder was the use of stock textures and going absolutely ham with detailing to create these trippy abstract themes and visuals, something that this wad has in droves. I think you also did a great job of pitching texture 'noise' in these maps correctly, adding to the visual appeal of the detailing without going into clusterfuck territory. The 10 texture and flat limit is a really nice balance and arguably just a good rule of thumb in the first place, giving concise and coherent theming in each map without feeling like an arbitrary limit (some community projects have fallen foul of that).
Combat wise this was right up my alley in terms of design and difficulty; good monster usage, lots of variation and i am glad that it wasn't (for the most part) completely ball busting, smashing through everything was super fun. The only fight i got really clapped by was the secret yellow key one in map 7, and weirdly that was probably the only fight i took issue with (ie hope the viles don't troll you, then hella circlestrafing cleanup if they don't? maybe i missed the correct strategy).
A custom hud might be the cherry on top here, if that is something you are interested in then hit me up, i'd love to contribute one.