I'm calling the Greif done.
The old decals did not stand up well to the chemical compound we call water. I found more recent decals from the Hobby Boss Bv 141 and was able to pick out a couple of Balkenkreuzs from that sheet (I had used a Montex Mask for the markings on that build). I ended up using the white Balkenkreuzs for the upper wings that came on the MPM sheet, but that didn't match the markings guide. The MPM sheet contained a broken-in-half swastika that I could not get down properly, so I went back to my spares box for a sheet of various sized swastikas that I bought way back in the 90s, and these worked just fine.
I opted against doing any of the stencils and wing walk markings after my first attempt somehow one of the wing walks managed to adhere to my finger rather than the kit without my noticing it ... by this time I was ready to just walk away from the whole thing. Instead, I settled down and decided my Greif didn't need any of those markings, as it already is somewhat of a fictitious build anyway.
The decal issue really ticked me off. Along with all the other issues this kit has (most of which I was able to deal with to a barely satisfactory level, at least), the decal issue was the final straw. How hard is it to get this right? That soured me on the entire build, and I just decided to go ahead and put the finishing touches on it.
A couple of self-inflicted issues that I noticed: when I removed the masking from the canopy, I found a swoosh of glue stain on one of the window interiors. No idea how that got there, and short of ripping the canopy off, buying an aftermarket one and re-doing, there's nothing I can do about it. Also, the instructions were often unclear on how certain parts were to go together. Take, for instance, the complicated landing gear struts. Each strut is comprised of 4 pieces. The primary strut part does include some raised detail that I took as to where to install the part to which the tire attaches, but apparently I placed that wrong on the outboard starboard strut. The tire is flayed out at such an angle that it would never function as intended. Of course, by the time I noticed, the strut was already affixed into position in the wheel well. I could have made an attempt at fixing it, but my thought process, clouded as it was by the decal issue, was that if I damaged the strut in such a way so as to make repair unlikely, I'd be faced with the prospect of an unfinishable model, or one that I would HULK SMASH. I decided to leave everything as is.
I doubt that I'll ever build another MPM kit given my experience with this one. But I'm glad to have a 48th scale build of Nazi Germany's one fully operational heavy bomber. The Greif sizes out equivalent to the Monogram B-17, to give you an idea of how big this kit is. She was too big to fit into my photo booth, so I had to set up the studio a little differently than normal to be able to take pictures that don't include the wall behind my work bench.
I'm going to take a week off from the bench, but I do still plan to build at least 3 more kits this year, starting with Trumpeter's 1/32 F6F-3 Hellcat.