Link and Emtron were on my "consideration" list for standalone DI. Link has the Voodoo Pro, which can run DI with their adapters and seems like a very advanced ECU, and Emtron looks solid as well. My concern on both of those were the same though. No one has really done the LT4 with them, and I don't particularly want to be a trailblazer. Setting up all of the base tuning parameters for DI is fussy, and I don't expect much if any support from either vendor to dive into the unknown on that. It's the same reason I've not played with MS3 Pro on things, even though I love the ability to customize EVERYTHING.
Basically I don't think either of those would have made my life easier/better than just using HP Tuners on my OEM ECU. The Holley, I just don't trust for some reason, it was very expensive vs. configurability, and I'm not in love with their support. Honestly if Haltech had a DI path, I'd have been all over that as I really like dealing with them.
All that in mind, JRR and Motec have done these, and I've found a lot of good testimonials on their stuff. They have done the categorization ahead of time and were willing to jumpstart me with that, which takes a bunch of time off of my tuning effort.
After some more research (we all research more after we buy... right?) it looks like the firmware I'm running will let me do a little more with CAN than I thought. I might even be able to creatively customize the configurable CAN outputs to negate the need for my CAN gateway. Maybe. I also have a little more IO available than I initially realized. I thought I had exactly what I needed to run my basics, but I have 6x more programmable low side controls, which lets me do some more fancy stuff (and also add more features I was doing in my control box). I can also put an E888 on it and get a few more I/O and 8x EGT, because, why not.
Motec M1 Tune is a little different than other software I've played with, but it seems pretty logical once you sort out the thought process on how you configure the ECU. All of this, of course, is just theoretical until I actually put the thing together and see how it works. There is still a lingering possibility I might do a dev license on the Motec at some point to totally customize things to EXACTLY what I want, but time will tell if the costs justify any small benefits in this chassis/build.