I too have a very coarse beard, but it works for me. Did you gentlemen splash your face with cold water or do any type of prep?
Maybe this is just a case of YMMV.
The first time I tried this, I skipped my normal prep - which is the OCM.
I just spashed cold water on proceeded to shave using the coldest water that would come out of the faucet. I experienced a bit of irritation and redness.
I wanted to give this a fair shake, so this morning, I did my OCM, rinsed with cold water, rubbed my face with an ice cube and shaved using TOBS Avocado and a Merkur Slant with a Personna blade and went with WTG, I rubbed the ice cube on my face and then went XTG and did a last ice rub before going ATG.
No irritation and very smooth. I can honestly say that my face looks better than ever.