I got my Mariner in today and just shaved with it. I don't think the quality of the plating is as good as the Muhle and the handle is far too small for me so I promptly put the Mariner head on my Cooncat Bob American Bullmastiff XL handle that my Muhle R41 head was on.
The Mariner definitely feels like the blade is flatter aganst your face. The domed head makes it harder to get under the nose. I shaved with it using a near vertical angle (steep?) and used a Treet Platinum blade. Prep was a hot shower and soap was MWF.
This is a very aggressive razor. I need more shaves with it but right now I don't think it's as aggressive as the new Muhle R41. It seems very close though. I recommend it for those seeking an aggressive razor albeit with the bigger handle or one of your own choosing. The short handle is toy like and not worthy of such an excellent head design. I did my usual 2.5 pass shave (WTG, ATG, touch up lip and under chin) and got a BBS with 2 small nicks on my neck.
I will try it with a better blade tomorrow. I am happy with my purchase so far.