I can confirm
I replaced my ER6i's with a pair or the HF5's. I've worn them on all day rides, two week trips, daily use on my bicycle commute, and they fit fine under both the dirt and full face helmets, and sound great. The cord is way more durable than the ER6i's. The filters are different than the ER6i's, so if you've stocked up, you'll take a hit. Also, I wasn't able to find aftermarket filters like you could with the ER6i's.
"I came into this game for the action, the excitement; go anywhere, travel light... get in, get out... wherever there's trouble, a man alone... Now they got the whole country sectioned off; you can't make a move without a form." --Robert De Niro as Archibald 'Harry' Tuttle in Brazil, 1985. The Mobius Trip index | Spot tracking live 4/18-5/4/13 | AdventureLoft™ Tent Space