Same head like these: 1904/1906, 20C, 23C, 33C, 34G, 38C, 38HD, and 38M. Not very aggressive head.
Maybe slant is a bit smoother but I think the smoothness depends much more on your blades and lather.
I get an irritation free BBS shave in 3 passes with very little clean-up with my Merkur 38C HD .
Is there a similarly efficient/aggressive razor but smoother shaving ?
A Merkur Progress set to 1 or 2 would be as aggressive, but probably smoother. I am also not a fan of the 38C. In my experience, many blades that did not work well in the 38C did work very well in the Muhle R89. One blade that does do well in the 38C is the RedIP, also the Walmart Personna Platinum Chrome.