I had a look at Vicious:
1) Dividing 3 by 2: Remove the two imploders. Change lix count to 30/30 or even 20/20, because I release the crowd while there are still 7 lix in the hatch.
2) The Last Laugh: Reduce the number of imploders to 1, because the save requirement is 3/4.
3) Lixster Quadrille: Remove the two fling-bomber and the two cubers, because the save requirement is 80/80.
4) Laser Deathroom 1: Reduce the number of imploders to 1, because the save requirement is 49/50.
5) Trapeze of Weird Blue Blocks: Remove fling-bomber.
6) Toccata: At the bottom left corner it is possible to build one stair so that lix from both sides may walk up the fence. However one has to place this builder frame-precise! Otherwise either the lix from the left may not step up or only one brick is placed before the builder turns. I found this pretty annoying.
6) Thomas the Climber: Reduce the number of imploders to 1, because the save requirement is 49/50.
7) Matter of Perspective: Remove the fling-bomber.
8) Survival of the Craftiest: Remove the two fling-bombers.
9) Dream the Impossible Dream: Remove the two fling-bombers and the two cubers.
10) Chasm: At the top left corner, one has to start mining rather early. The reason is, that otherwise jumping runners will start too high and vanish through the top. In my opinion this makes the level more fiddly than is actually has to be.