I have completed this pack for NL Old Formats, so I have attached my solutions. This is the very first time I have ever played the pack, and I got to say I was quite impressed with a lot of the levels. I didn't really feel any real challenge until I reached the Taxing rank, but I really felt the difficulty once I got into Mayhem. The first real stumper for me was Taxing 28 - Swiss Cheese, surprisingly. Took me quite a while before I saw the solution. The next hard one after was Mayhem 8 - Four Houses, although it's a difficult one to execute, not necessarily a hard level. Mayhem 24 - Pyramid Scheme, Mayhem 25 - Main Floor, Please, and Mayhem 26 - Parking Garage were all difficult levels, I thought. I also remember playing Mayhem 24 and Mayhem 25 from somewhere. I don't remember where, though. Might had been RotL, although I think they might had been in some Dos level packs as well. They were difficult only because I couldn't remember the solutions to them. It's been a very long time since I played them. There were other levels in this pack I remember playing from somewhere before as well. I also remember Mayhem 8 from somewhere. For Mayhem 26, I got to say that it's one very awesome no builders level. I think I can see why it won as a contest level. The solution is quite ingenious, although it took me a while to spot it.
The only level that seems to be completely broken is the very last level. There is a fire pit just before the exit but the lemmings don't burn in it. I checked video solutions for that level, but no one goes through it and instead digs before it and then bashes. Needless to say, them not burning in it took me by complete surprise.
Also, I ran a mass replay check for the New Formats version, and 6 of my replays failed: Mayhem 5, Mayhem 14, Mayhem 23, Taxing 8, Taxing 9, and Tricky 7. Mayhem 5 fails due to how I made use of the solid ceiling in Old Formats, since it's deadly in New Formats, Mayhem 14 fails because the trigger area of the mashers is much bigger, Mayhem 23 fails either because my builder assignment was too late or the trigger area of the trap is bigger, so that's a very easy fix, Taxing 8 fails due to the expanded OWW, Taxing 9 fails because a builder assignment at the end is too early, so that's an easy fix as well, and Tricky 7 fails due to missing the exit trigger area after the basher finishes, so again easy fix. One was also undetermined, and that was Mayhem 3. The replay is just completely broken, I think because of how the level originally had an upside down entrance.
Overall, very nice pack, although I noticed a lot of the timers in the Mayhem rank are very huge.