Good job and I can see quite a few things to like about this list:
(1) few different builds (air assault or demon engine heavy) that look fun and different from what you can do with BL.
(2) a few 'meh' units(Bezerkers) and some one dimensional units(plague marines) suddenly look a lot more promising in this list. Always good to see hardly used models back on the table.
(3) I don't see you being able to build a TS,EC,BL list but better, which I imagine wasn't easy to pull off.
Other cult lists are still different, even if they arguably have other issues.
The suggestion to increase Brass Scorpions to 4+RA sounds about right to me. (Without shields I see crossfire being overly an issue) But we'll try the list out in a few weeks and see how it goes.