I received the Seidio 1750 yesterday and charged it overnight. Right now I am at 66% battery left (at 4:30 pm, and I have been using it a lot today.) Until yesterday, with the stock battery, I could not go through a day without having to charge at some point for about 30 minutes during the day. Needless to say, I am very pleased.
The one thing that I noticed is that this battery is thicker than the stock battery (which makes sense), but is just thick enough that the back cover no longer completely engages; there is a slight gap near the volume buttons on the left side. Since my Eris lives in a case, I am not too concerned, but it is worth knowing if you are thinking about this battery.