The voltage drop(rather sag) you talk about is about the type and condition of your cells and the effeciency of the mod...
There are some reports of not the greatest battery-life because it has a cut-off at idle of 3.4v, where as Eskie stated, usually mods have a little higher cutoff like 3.1 - 3.3. Also, the display stays on for 20 secs I believe, which is a little on the high side and non adjustable. I don't know what the specific effeciency of the mod is, which is the true mark of how long it will last between cell-changes + the cut-off, but still, it's a 2 cell mod, so you should be fine no matter these "issues" imho, and I don't think you will regret getting it honestly.