I guess dhd battery is a pain in the a** for everybody, I suggest you to go for sensation xe, evo 3d type batteries. There are plenty of ways to do it (with battery door or without) I was personally using without battery door because I was already using silicon cover for all phone. Btw you need to apply a small copper wire for external wireless antenna which is already built-in with your original battery door. Search for thread in this section you will find Evo3d battery thread. I have changed to HOX but still my wife is using my beloved DHD with 1950mah Mugen. Believe me it gives equal amount of satisfaction for this money. If you don't want to spend that amount, go for original Amaze 4g battery (which has the highest capacity when compare with evo 3d if I don't remember wrong) still you will be satisfied with battery life.
Please don't ask me, which rom am I using or how is battery life. It depends on people and how they are using.
I can give several examples, heavy usage with all the time 3g, bluetooth, mail sync, whatsapp, viber, browsing, auto brightness but no games and no wireless: it will handle 1.5 day.
Moderate usage, all the time mobile network on, a bit whatsapp, several regular calls, a bit browsing, no gaming and wireless off. My wife can easily manage for 2.5 days.
One more thing, if you will have 1950 mugen, your battery will stuck at %15, don't panic it will stay there for at least several hours (according to your usage ofc). Its some kind of a bug. I don't know if somebody found a solution.
I hope, my reply will enlighten you a bit