My DS wore a helmet from 4.5 months to 8.5 months. He recently had it removed on 12/19. His head differential went from a 6.2 to 1.2 HUGE IMPROVEMENT! In fact, they said that at that particular office, they had never seen such a great correction number. You can't tell he ever had a flat spot. I am a believer in the benfit of helmet correction.
Back story:
He was diagnosed with congenital sternomastoid torticollis at 2.5 months, and plagiocephaly as a result. The back left side of his head was flat and his forehead on the right side was slightly bulged. His ears are still slightly misaligned (not noticeable at all) but the helmet does not correct ears. We tried from the minute we were told to do sleep repositional therapy, which help a bit, but not enough, so we opted for the helmet. DS also went to physical therapy once a week at Childrens and I also had an in home physical therapist once a week. Figured if we attacked it aggressively, we wold resolve the issue faster while DS was still fairly young and hitting major growth spurts...it helped tremendously!
We decided on the clear for various reason, mainly we were told they were more hypoallergenic and tend to stink less. We cleaned the helmet once daily with 70% rubbing alcohol, then a quick once over with DS usual body wash. DS wore the helmet 23hrs a day. I would take it off for an hour each night during bedtime routine. We also washed his hair nightly. We also decorated his helmet for holidays and events. I got some decals from blingyourband.com and also hit up the fabric and hobby shops and made decor for it. Beleive it or not, clear packing tape helped tremendously with some of the decor. I only ever had one rude comment as far as questioning in a judgey tone as to "what's wrong with that baby?" For the most part, some folks would stare a bit, but more often than not (80% of the time), people would comment on his cute "hat", some (mostly little children) would ask if it was a fashion thing or something else, but liked it either way. And some folks would tell me that they knew a child that had one or knew of a child that should've had one. Definitely a conversation piece! Lol. I never minded the stares, I would just give a "eff u whatever *** grin" in their direction, making them highly uncomfortable for being caught staring. It always made me chuckle. 
I was freaked out big time at first that he needed one, and the adjustment to wearing it was definitely on my end. He never minded wearing it. In fact, I kinda miss the helmet now as he's cruising around, when he had it and fell...no big deal, now, he feels the fall or bump on the crib...ahhhh I miss the protection it provided,,,and piece of mind for a worry wart FTM.
In the end, when I saw how DS didn't mind it and when I thought about the alternative (having a flat head, being picked on by some bully for being different, lacking self esteem as a result) I knew it was the best thing for us. And he only had it for 3.5-4 months...very small blip on the radar of time.
Hope this helped! Currently, I am enjoying putting hats on him again and physical therapy is now down to one therapist, twice a month. She's just keeping tabs on him until those first steps in walking. They just want to make sure that the tort indeed has been resolved and he isn't favoring a side with that huge milestone. ( which they see no signs for favoring a side or tilt anymore)
Good luck to you and your family. I know it seems like a lot to deal with now, but after the first week or two with it, it becomes normal, standard (in fact I would forget it was time to take it off for the hour!)
Piece of advice, it takes a week for their body temp to get use to the trapped heat, just dress LO a slight bit lighter than usual. Also, have them drill holes in the back of it to let heat escape. Also, it will be a bit loose at first to allow some room to grow, that looseness will go away after the first week or two. It's a tad annoying, but temporary.
Please feel free to PM me if you have any further questions.