Definitely not dull lol! They're quite a bit more difficult, especially with slow developers. Can't use comb/wattle color or leakage over wing bows as an indication. Also a bit more tricky to see saddles on black birds. For me anyway.
I hate sexing these fibro birds. They both look like pullets to me.
Be careful putting chickens in with drakes. Different plumbing on both birds. If a drake breeds a chicken, it will injure and/or kill them.