Any reason logistics shouldn't just have only two marks?
Well, it would break the symmetry thing we have going among the three basic command station types.
I would like to see some sort of increased speed reduction of enemy units as the Mk goes up. Kieth, you mentioned how the "what is the max speed I can have considering outside effects?" code is in a performance crititical loop, but how hard would it be to change it from (speedSoFor >> 1) to something like (speedSoFar >> 1) - N or (speedSoFar - N) >> 1? (Where N is 0 in most cases, but for Mk. II and up logistics stations, it would be higher) This would introduce issues with underflow and speeds being put at 0, which may require additional bounds checks, which you might not be able to afford in that code path.
If this sort of thing would not work, how about giving logistics stations Mk. II and up a gravity effect? That would require some balancing to figure out what good ranges and magnitudes for those gravity effects would be though.