The Flurry Unleashed (BF/The Goddess Unleashed, ~400k DPS [no ridiculous PoB stuff enabled])

PoB for build, with Slayer/Ascendant trees to compare: https://pastebin.com/PjHP4awK

Rationale for Build:

The Goddess Unleashed (TGU) may well be discontinued/replaced (with something better hopefully!) as of 3.1 so I wanted to both use that weapon and hopefully make a nice decent build on my own.

BF is OP so this isn't an amazing accomplishment really, but this build has:

-6K life
-400k shaper DPS (up to 1.5-2mill with flasks/all buffs active)
-10 ex budget (could be much more but this is realistic for me)
-No Vaal Pact (mistake? I figured I need regen to counteract TGU degen, right?)

I'd like some feedback on optimizing/min-maxing (within a 10ex budget or so). I haven't played it yet, will be leveling the character today, but are there any red flags or big optimizations you see? I have the Shadows and Dust rampage gloves already, I realize the steel rings are OP and I can just settle with two stone rings and take a little DPS hit probably.

I also can't decide on which class to go with:

-The Slayer version has about 1800 leech on hit, better phys reflect mitigation? (maybe not really if I go ascendant Slayer-Elementalist?), and about 20-25% less DPS than Ascendant.
-Ascendant (Marauder/Slayer) version has 20% more DPS but only ~900 leech on hit - which still seems pretty good with 7-8 attacks per second, but I don't know how exactly leeching works without Vaal Pact, tbh. I could also go Slayer/Elem to get the best reflect mitigation.

HELP! :)