Fitbit Flex vs. Fitbit Charge HR

I didn't have a flex, and went straight for the CHR.

I haven't had any skin reactions, and where it unless I'm in water or it's charging. I find I charge it about 2x a week, maybe 1.5 times. I have it set to only sync when I tell it to, which saves on battery life.

I can't speak as to whether the HR portion is really accurate or not - I have never used a chest strap, and the idea doesn't appeal to me. However, I've been using the fitbit's caloric burn + MFP food input to keep within a deficit, and the weight has been coming off (except for the two week hiatus I took and gained those 5 lbs back... Ugh... but that's my fault, not the fitbit's fault).

I do find that the HR reading will help me push up into the higher HR range while running, just so I can see the "peak" line on my dashboard after going for a run. I also like that once I push the "workout" button, it automatically takes all the metrics for me - time, distance, pace, etc. I do a mix of lifting and running, so it's a little less useful during lifting sessions, but it still times me, measures my heart rate, my steps between sets and gives me a calories burned (usually around 100 for lifting, but I walk a lot between sets).

All in all, I am a fan, but really have nothing to compare it to.

I have the Charge HR. I haven't had any problems with rashes or irritation from the band. I wear it all the time except when showering or doing dishes. The heart rate measurement seems to be pretty accurate. In the middle of a workout I've compared it to both the manual heart rate measurement and what it says on the treadmill and it's usually no more than 5 beats off. For me the battery life is fine unless I put it in workout mode and forgot to turn that off I usually have it in workout mode for 6 or 7 hours a week and charge it maybe 2 times a week.

I'm interested too as I'm thinking about the HR one. Seeing my HR helps me know if I'm really at the limit or if I can still push on. I should be able to do that in my own head, but it gets ugly in here.

I have the Charge HR and I wore it a few weeks and never had the pain or rash people talk about until one day I fell asleep with my hand under my head and slept this way for about an hour with my head pushing the Charge HR into my arm...after I woke up I had a terrible pain in my arm....thought it may go away but I had to take it off. Left it off a few days and put it back on and no pain at all. I also recommend wearing it loosely like they recommend. I think wearing it too tight could cause pain.
Keep the all day sync and the caller id off and the battery lasts much longer.
Oh I have the flex too and I like the Charge HR so much better. So much more information.