16GB is manageable. People have done it for years with the iPhone. The EVO started out with 8GB. So... I'm not sure how our usage patterns have really changed that much. That said. It is a big factor because it's twice as much space. However I'm not sure the battery size will matter much.
Here's what will matter. AT&T has fallback to HSPA+. Sprint does not. This is the number one reason why I'm going from Sprint to AT&T. Number two is the savings from a family plan. Number three is the phone design.
I mean no offense, but people who say it's a personal preference or that they like the EVO 4G LTE design...I think they're just saying that to convince themselves it looks good. At heart, no one thinks that's a good looking phone. That was my first reaction too. Not that "oh it's slightly different and black with a kickstand, cool." No, it was "WTF?! That's ugly. Let me take a second look to ensure it really is as ugly as I think." It was. It is. Sorry. But I was willing to simply put a case on it and deal.
I enjoyed Sprint for years, but I just don't think they'll have the success of the original EVO with this one. Their 4G network is in a REALLY bad place. For most folks, by the time LTE is in their area, the new generation of phones will be out. So this really leaves most people with buying a phone with a feature that they can't use. ... and I'm not even talking about being in a rural area... I'm in the San Francisco area! AT&T at the beginning of the year rolled out LTE now to NYC, San Francisco area, and parts of Texas like Austin. Being a tech person...Guess where I spend all my time? One of those 3 places. So it's utterly embarrassing that Sprint won't have 4G in all of those areas for at least another year. Note that I didn't go with AT&T in the past because Sprint WAS better in these areas. No more. The networks have shifted around and that should be a very big factor in your decision. If I was in Dallas I might stay with Sprint to be honest.
So you're trading looks and 4G over 16GB and a tiny bit bigger battery. I don't know, I just couldn't give up the 4G. I actually never used the 4G much on my EVO because of the battery...When I did, it was so fast. Night and day. So I'm really looking forward to using 4G without ANY worry.