I considered using another battery too, but this option has multilple advantages:
1) It has 1900 mhAmp, so it lefts 500 mAmphs free to make another charge.
2) I'm using two smartphones, so I can charge both ones.
3) I don't need another charger or charging it in the phone and removing it. I just charge the emergency charger and I can use the phone again.
BTW, my ZTE Blade seems to be the AMOLED version, with low battery consumption. I'm using stock GB firmware, and after a day using 2G network, WiFi, playing Angry Birds for 30 minutes, using Whatsapp and a few phone calls, I have 30% left. SO I'm quite impressed with battery life, hope it will be as good as my Samsung Wave (I use it around 2-3 days with no problems)
I will make a full review when I will receive the charger.