I know where you are coming from Geoff. I've already played a bit with the standard Apogee crossover with the man that restored my original pair, tuning the MRTW ribbon by ear. Actually, that isn't completely true, I knew what I wanted in terms of FR beforehand. Digital EQ makes it easy to know where to head.
However I just fancy messing around and trying a few ideas to see how they work out practically. The only way of doing that at reasonable expense is to do it myself.
I want to see if I can raise the bar still further. The Apogee Duetta Interstella project raised the bar over the standard refurbished Duetta by quite a bit. However, these things are NEVER perfect, and never will be. I reckon, though, with some effort, I can do better still.
The next time I am between contracts I'll apply some serious effort to it.