Yeah, I've done the crushed joiner thing in seven or eight spots and, frankly, every one was a fraught process. With my yard and industrial plan, in the end I think there are going to be close to 100 transitions, so something in that process had to change. Not nearly as clunky as Atlas insulated joiners, which I have been using in certain instances such as crossovers, albeit foreshortened to reduce the mass. I may mod this transition joiner for C55-C55 for that very reason.
The gap is not as bad as you think, hard to see but there is a filler tab.