IMHO this is way better than Excavation. Excavation has minimal interlocking, meaning there is much more opportunity for a grenade to get lost in the cracks on the floor, ruining gameplay a bit. It looks like you took your time to do this, and that is something to be proud of. However, if you want even more kudos, try geomerging those grav lifts. The tutorial to do so is found
here. You have to geomerge the wall or whatever you're placing under the map differently, but it shouldn't be too difficult to do once you get everything under, as I have done this myself two separate times on one map on Sandbox. It will be worth it in the end, and people will praise you for it and maybe end up a little astonished :P