Allen's Hummingbird?

First saw this hummingbird yesterday, and then again this evening at our feeders.  The photo is a bit fuzzy, but you can clearly see that it's an adult male with green back and crown.  I couldn't see any red feathers on the back.  Hopefully it will hang around and I'll have a chance to study it more closely...maybe even get some better photos.  Apparently there is the occasional adult male Rufous Hummingbird with an entirely  green back, but they are described as anomalies, or at least quite rare.  Noticed this bird also didn't behave with typical Rufous pugnacity when it was sharing the feeders with a female Archilochus-type hummingbird (Allen's are said to be less combative and aggressive than Rufous are at feeders).  If it's an Allen's, and I'm thinking that it probably is, then it's a nice addition to our yard list (as well as being our sixth hummingbird species!).  Of course I would welcome any opinions or thoughts about this bird.