Owning three Howards and tilling commercially, I've went through a lot of tines...
I prefer the round tines, I can't see where the square tines to any better job and the round tines do last longer.
I only use Howard tines, why ?, because I till in some pretty awful conditions, and hit quite a bit of trash and lot's of rocks, Howard tines last longer!
Howard uses spl. bolts, when the going get's tough, be careful what bolts you use! I've had NO LUCK AT ALL using box store or yuppie farm store china bolts, I use Howard bolts or I go to a RELIABLE "nut/bolt store" for my bolts, making sure the replacements will work PROPERLY for holding the tines on. Yes they cost more, but I don't loose tines because of them either!
BTW, I RARELY use a bolt more than one time!
SR