I'm wondering how practical it is to test more than 1 level in a row? I mean, you are supposed to acquire powerups and stuff, so when you test a x.2 or x.3, x.4 level you have to estimate the power the player may have accumulated. Not easy.
My technique would be to temporarily drop powerups/bombs at level start, so you can test the level easily.
Do the editor have an option to increase/decrease monsters energy? Would be cool if you want to make it harder/easier and finetune the whole level set in post-production.