I thought I'd chime in and share some info for anyone who's looked at this project and may wish to do something similar. I no longer have the speakers hooked up and drivers have been pulled. I ran into a few major issues that I didn't account for and had to experience for myself. The above impedance graph can be ignored, I was still figuring out impedance measurements.
1. Either the cabinets vertical dimensions or the room caused a big resonance in the upper bass, approx 178hz. The port showed a resonance here and plugging it didn't seem to fix it for the most part. EQ helped but it kinda seemed like removing that energy resulted in a thin sound. I tried dampening and adding extensive bracing to dampen what I'd consider a fairly lively cabinet. Nothing really helped. None of my other speakers exhibited this problem with the same placement.
2. These things just image pretty poorly. My initial impressions were that of good imaging, but that was really a honeymoon phase thing I feel. I think this is largely in part of the wide baffle. I've heard a lot of conflicting opinions on baffle width and it's relationship with imaging and dispersion. I did try a waveguided and non-waveguided tweeter with differeing xover points and was disappointed with both. I think this is really something you just need to hear for yourself to decide. Comparatively all my narrow baffle speakers image quite well with a depth that these big speakers just lack. These big speakers call more attention to themselves and don't really 'disappear' at all. A lot of people I talk to argue that small baffle speakers are largely more common due to manufacturer constraints (easy to ship small speaker, fits in most homes better) but I'd argue when executed well, they just sound better. I'd wager there is a reason companies making state of the art speakers are keeping the baffle widths small.
3. These things are super heavy and I can't move them by myself. This makes any modification and analysis super hard. I pulled a back muscle moving them
4. Active filtering for three ways kinda sucks. It's just too expensive for me to do it to degree that would satisfy me. I'm currently using my onboard sound card but the jacks are very loose, one was pulled out by my cats and sent nice hum to the mid range (tweeter would've died probably if suffered the same fate). It's all unbalanced and I don't care for that, I have a lot of pro audio and musician experience so it's XLR or TRS or bust IMO. RCA and 3.5mm are junk connectors to me.
This was a ton of work just to learn what I don't like, but hey at least I know. There were some positives, like having effectively two subs in front of me, which let me put my two subwoofers behind me and enable a sort of multisub setup. I can tell you right now if you want even bass in your room, just go multisub. Forget wasting money on 'bass traps' and such, this is the most even low end I've ever had and it's great. Even without DSP just adding subs evened things out a ton. It's kinda crazy to just walk around the room and hear the same bass everywhere.
My current plan is to save the 12" woofers and build sub boxes for them, continuing to use them in a multisub configuration. I'd like to keep doing diy speakers, but man it's getting harder and harder to convince myself it's worth it. If you've got high standards it seems quite hard to make something better than what you can buy. If I dive in again, it will be a coaxial driver (not many good ones for DIY) on a thin baffle. KEF LS60 paper is going to be good reading for me. Even so it will be hard for me to justify not just grabbing a pair of KEF floor speakers.