Actually, I'd agree the grip-to-tip direction is the most important, as this will be responsible for most of the wobble, however, if you don't center it along the lead-to-tail direction, there would probably be performance issues that only appear at certain higher RPMs, where the forces on the airfoil start to count more. Tho, the effects would probably be hard to notice if the grip-to-tip CG was out.

As for the consumability of blades goes... I do what I can to prolong their life. I've had great success with fiberglass/CA versus the plastic wrapper it comes in.. Also, since I'm adding so much weight, I've taken out the lead (I was disgusted to find it in there, really) and replaced it with a small carbon rod (on my flat blades) and balsa to fill the gap before glassing 'em. My glassy sym blades are only 1.5g over stock, but took me something like 6 hours to prepare..........

I've had several pretty gnarly crashes on my stock blades, and they still fly great. They've survived well with 2 or 3 layers of fiberglass in the leading edge/tip. The consequence of making the blades rigid is that the shear pin goes often, and maybe a higher risk of bending the shaft or spindle... and I've shattered my tail boom... but those are acceptable risks for me since all that's easier to fix than shattered wood that needs to be balanced.