I am a doomer, and I like community wads as much as I like Plutonia. I came up with the idea of scaling IWADs and community WADs by difficulty in 10 levels. From 0 to 9.
0: Not an accomplishment to complete, even on Nightmare difficulty, Nightmare.
1: Playing this is pretty easy, even on UV-fast.
2: A little bit harder, but still pretty easy.
3: Medium, usually pretty fun.
4: A bit harder, but it’s not the hardest.
5: Kinda hard, but still fun.
THE ULTRA-FILTER
Doomer, if you have completed WADS which rank 5, then you are ready for higher ranked WADS
6: Pretty hard, a bit of skill is required.
7: Very hard, you might want to practice on a Level 4-6 WAD before playing this WAD.
8: VERY hard, skill is required.
9: These WADs are the greatest challenge, only the best Doomers can finish these WADs. If you manage to complete one, you are truly a supreme Doomer.
Here is a scale, which uses the Iceberg template.