I've had the Evo Shift for about a week now. I was using a Hero that was rooted and using CM6.1.
I think the battery life on the modded Hero was a LITTLE bit better - but not consistently. Because I was using nightly builds of CM6 - things would get weird now and then. But with CM6 installed and working properly, the Hero's battery was - compared to the stock build - amazing.
It's fairly close so far with the Shift. Only with the added benefit of rock solid stability. The only trouble I had was when Z4 Temproot seemed to cause some problems and my phone rebooted - and then I had the Z4 process sucking down battery power. I'm still getting that sorted out. But it's rooting - and that's the price you pay, especially this early on.
All that being said - the phone's battery life has been impressive. Especially because I've been playing with the phone constantly, and using it heavily. Today I used it listen to music in my car, send a bunch of emails and texts, several voice calls -- while being connected to my bluetooth headset. My screen brightness has been at least half-way up (it's usually down to like 30%) because it's sunny and bright here today. I also played a little Angry Birds while waiting for a meeting...
Though I never had 4G on, I had wi-fi on a bunch by accident, which was probably an unnecessary drain. And with all of this activity - and never connecting to a charger (not even in the car, I forgot) - I'm at 63%.
Now, I live in Los Angeles, and Sprint signal here is crazy strong almost all the time. I had signal on the 3rd level of a parking garage today. Which is always a fun way to mock my business partner. If I even say "parking garage" his iPhone drops a call. So maybe this signal strength is a real benefit to me, I'm not sure...
Also, my experience so far with this phone is also that -- like the Hero -- it seems to charge very quickly. A little charge in my car, or in the office, or even connected to my Macbook via usb -- and I can stay over 60% all day.
And yes, even with the Froyo 2.2 on the Hero, voice calling and search was fairly useless. Having the Shift I now get how useful it is. The Shift is just faster in every way possible.
Oh, as a point of comparison, I also used my 16-month old Hero battery in the Shift. For some reason, my ORIGINAL stock 1500 battery for the Hero is stronger than the 1750 Seidio battery I bought. I've never had Seidio batteries retain their capacity for that long. But the Hero battery in the Shift worked well and I felt was pretty damn close to the Hero's battery life.
And - keep in mind - I'm just playing with the Shift all the time. It's a new toy. So sometimes I just turn it on to look at the screen because it's so shiny. Once the initial awe wears off, the battery life will be even better!
If I had one small gripe - it's that the Shift is SLIGHTLY heavier than the Hero. Something I'll be used to in about a month or so.