Nice setup! I was actually contemplating the EXACT same setup just a month ago. I've got the DB4 and the ZeroFlex240 as well! I decided I didn't want to buy all new parts just to have Thunderbolt 3 and a few percent speed improvement. I'm waiting for 2+ Thunderbolt 3 ports and a bit better support for them. I'm using a Impact Vii, i5-4690K, HDPlex 300W PSU, M.2 NVMe, 4x hdd's. I may end up making a build log here when my MDPC-x sleeving gets in and I finish that up!
Also, just a heads up, you have the passive heatsink setup a bit differently than Streacom recommends. Check out page 12 in the Streacom Manual. They say it should have the heatpipes outward facing, directly in contact with the side of the case. Though, I am curious, what do your temps look like? I am curious if they'd be any better. Have you done a stress test and recorded Idle numbers? Also, do you plan on getting the LH6 Heatpipe kit? If you'd just like a lower temps, it may be worthwhile! I'm currently working on some custom bent heat pipes so I can install mine since my Power Daughter card gets in the way.