I have the HOS collector set in plastic (3.75" king) and I must say that I'm disappointed with it. One of the mitres is signifcantly narrower than the rest of them, like a production defect or something. And the plastic work seems to be shoddy in some places .. around the ears of the knights, the seams, etc. It's still better than the typical club special set but I expected more out of HOS, at that price point for a plastic set. You got a great deal on those pieces!!! I would not refuse to play a Tournament with them! Referring to the wood set of course.
I know this thread is about PLASTIC sets -- but I just bought a very cheap wood set for tournament play, Chesscafe international (german knight) in rosewood, weighted. I only paid $22 for the set (the sale is over, but they're still only $33), and I'm very happy with them. At that price point, it can compete with the higher end plastic sets. Of course it is a very basic design but seems like it will be very durable which is exactly what i want.
I have the HOS 4 inch King collector series & am quite happy with it. I did have to buy a 2.5 inch board so it fit properly though.