Tensile strength is one of the least important, yet overemphasized factors in chain selection. Anything over around 5000 pounds is adequate for a YZ450, a fact borne out by the extremely small number of chains that you see actually snap in two. Wear resistance is what makes them last.
The DID erv-3 has a tensile strength 1000lbs. higher than the Regina. 7642 for the Regina and 8660 for the DID.
This is to be expected with any new chain, and the fact is it probably needed adjustment in the first 30 minutes. If you treat it right it won't need it again for a very long time.
Well, I rode yesterday with my new Regina chain and I can pretty much tell that the next chain I buy will be a Regina ORN6. Two hours of riding and it needs to be adjusted already.