Flurry 7 - Okay, I beat it now. That was a GREAT level! Nice and short, but still challenging.
Flurry 9 - Using block-bombers as substitutes for other destructive skills is another thing you're doing far too much. It does not add any difficulty inherently - the reason it works for Mayhem 26 is because it forces you to take the route through thinner obstacles. When just used as a general substitute, all it does is make the level tedious.
Flurry 10 - Another really good one!
Flurry 11 - And another!
The bomber timing needs to be very accurate, but for this level, there's not that much that can be done about that.
Flurry 12 - Good level, but I'm not quite sure what the bashers were meant to be for?
Flurry 13 - Major backroute here... unless that's what you intended, of course.
Flurry 15 - Another excellent one!
Flurry 16 - I'm sure I played another level like this one lately... might've been in GeoffLems? Though regardless, this is a very well known trick by now and this setup has been done a hundred times (including in some of my own levels - the intended solution to PSYCHO 30 from LPDOS uses this at one point, for example). Re-using the trick isn't inherently bad if you can come up with a new way to use it (or a new combination of tricks to use it as one part of), but re-using the setup gets kind of boring.
Contrary to what you say about them being "rare", there are a lot of builder-heavy levels this time around - although definitely not as many as in the original cLemmings. Levels that are long and tedious without nessecerially being builder-heavy are also... I wouldn't say *common*, but a bit more frequent than they should be. There's a lot of buried exits that seem to be so just for the sake of it, and a lot of levels that use bombers (although at least with blockers) in place of other destructive skills which does little but make the level annoying, unless there's a reason why bombers are more effective or (as in the example I gave before of Mayhem 26) the limited range of a bomber actually forms part of the challenge.
That being said, this pack also contains some of your best levels so far, too. I notice you mention that you put together many of the Frost levels in one day - that is often a recipe for disaster. Rather than throwing together low-quality rushed levels, take a bit longer to release the pack if need be. You're not working for a professional developer, you don't have any set release date to stick to. I'm also not sure if you've done this the same way as you did with ONMcL, but also don't focus on one rank at a time - just create levels, and when you've done one, put it where it suits best. If you find a really good more-restricted solution to a level, move it into a higher rank and reduce the skillset - it's easier to create a new low-rank level than it is to create a new high-rank one.
And yes, I still have one rank to go - going to play that now.