generally better off if you haunt ebay for the same thing used for the same price or less with a hardened head. A used square with a hardened head will always be square and always be smoother (hardened steel over hardened steel burrs less, and already has less friction).
I've purchased about three used high quality non-hardened squares, one mid-grade unhardened new one (PEC) and three older hardened head squares (two lufkins and an old starrett if I recall). All three older hardened head squares are better with better action than any of the others, and squarer than the PEC type and smoother working by a mile (and cost less - about $45 each).
Nobody needs three, but the three subpar squares are gone to ebay, the PEC one I just threw away as I recall - i think it was bad enough to call it defective, and I keep one hardened head square at the bench and one where I typically saw rough lumber 20 feet away in the shop so that it's where I'll use it to mark wood.
