Also that MSX-O-Mizer thing sounds interesting, it's really better than BB or Pletter?, and how about speed (although decompress an executable is not a task that needs too much speed)?
Yes, MSX-O-Mizer is better than pletter5b.
The depacker routine is shorter and the compression gain, on my 2K files (i.e. pure asm code and few data), is about 4%-8% depending on the size and on the type of data. Actually I've found even larger gains when compressing larger files (12% of gain against pletter for screen 2 images).
The contra are:
1) it is slower, but I cannot say how much wrt pletter
2) it needs some bytes of ram as temporay buffer