For me it's a gimmick. Historically they made sense once (I think mor because of the torsion than the slant positioning), but nowadays I do not think so.
Esp. the Fatip OC Slant doesn't do it for me, it gives me irritations but leaves too much stubble. The only slant I like and that gives me a good DFS close shave is my Fasan OC Slant form the 1930s or so. But I don't think, that beeing a slant has anything to with it. I also had a Merkur 37 which was just a bad shaver for me.
Esp. the Fatip OC Slant doesn't do it for me, it gives me irritations but leaves too much stubble. The only slant I like and that gives me a good DFS close shave is my Fasan OC Slant form the 1930s or so. But I don't think, that beeing a slant has anything to with it. I also had a Merkur 37 which was just a bad shaver for me.