I tried this for a while with several different characters and found some good and some bad:
The good:
1. Very quick tilts - this along with the overall increased speed and priority of tilts over smashes meant that I hit before I was hit often.
2. By pressing the c-stick in a diagonal direction in air you could easily perform a Nair even while pressing a direction on the control stick.
The bad:
1. Some characters (like Ness, Marth, DK) have great spammable Dtilts that can put the kabosh on ground approaches but with attack c-stick on when I tried to do repeated down tilts my character would sometimes do a small hop straight up (yep, while pressing DOWN on the c-stick they would hop UP) and with maybe or maybe not an attack.
2. Sometimes if a character is behind me I would use a side smash with the c-stick to quickly turn and attack them. With c-stick set to attack pressing in a direction behind you ends up performing your standard A attack IN-FRONT of you so you are left attacking the air while your opponent is free to abuse you in any way they want.
Overall, I felt that these good and bad things about balanced each other out and that I could work through the bad. I tried this config for a while but went back to smash c-stick because I found that I just wasn't doing as well. I might have slower tilts, smashes when I want tilts sometimes and Fair when I want Nair sometimes but when something undesirable happens it is because of me and not some stupid, frustrating glitch . . . and you can't forget about fast smashes.
