Simon and I have noticed that the new digger is slower than the old one, which could have an unwanted effect on some existing levels: if the spawn interval is 50, a digger on a horizontal floor would get deep enough to trap the next lix behind him with the old digger behaviour, but will not with the new. This can be fixed (if doing so has no ill effects on a particular level) by raising the initial SI to 60.
I've already found one level where this change is essential: Buridan's Lix. Are there others?
Very good point. Heed the traffic Light needs to be changed as well. I will post a new version in the level pack thread soon.