I have never heard of using 6 blades before. But it seems like the advantage would be to run 3 mulching blades. 3 Blades are cheaper than 6 of course, and if you have mulching blades under the deck anyhow, you are mulching grass. So there is no need for the conventional blades, which cut and discharge the clippings. Then you have to pick them up somehow.
A lot of people out there like the Gator mulching blades but there are a few other brands on the market.
I use conventional blades and a side discharge on an old John Deere 111 but I have to use a one way, outside circular pattern to blow all the grass to one side, eventually blowing it into the woods at the edge of my lawn. Mulching would be easier for me and probably more healthy for my lawn, but I am not in the position to convert at the moment.
Good Luck, let us know.