I have an Ontario Navy Mark III knife made of 440A. The edge grinding on the right side of the upper edge is very sloppy.
I would be suprised if the 440A Marine Combat turned out to be any good. First of all, 440A is a barely adequate stainless steel. Also, Ontario does not have the best reputation for quality control and heat treatment.
I can't remember the maker, but once I ran across someone who makes a replica of the Marine Combat in 440C. Of course, the price was much higher than that of the Ontario Knife - $235, I think.
Kabar seems to have the best reputation for factory knives of that type. One of the Next Generation models is made with D2 steel, which is miles ahead of 440A.
For a low cost Marine Combat I would get the standard carbon Kabar version. My next choice would be the Next Generation in Swedish stainless steel, which is possibly much better than 440A.