Yes, I would go for that. In photograpy one can't have too many batteries - or memory cards.
I had my share of trouble with off brand batteries for my Nikon, so I went back to official ones. Off brands were unreliable and with a tendency to heat up both during use and recharging. I'm sure Anker would make great camera batteries.
And, now that I come to think of it, why not standard size rechargeable batteries as well - you know, AA, AAA and so on?