A lot of the new helmets have different liners for one shell size so you can get a liner for riding with hair down, and a liner for hair up ;) I just did that with the Jin helmet I ordered through ISellTack.com, and I'm waiting for it to come. I'll let you know how it works. I'm a 57" with my hair down, and 58" with my hair up and both fit in the M shell so I ordered both liners with the helmet. The nice thing is the add'l liners are less expensive than ordering a second helmet. As soon as I get it, I'll let you know how it is!
Otherwise I have my Ovation schooler for hair down and my GPA for hair up but I got sick of my GPA because it's 1) 8 years old and 2) it still and always has given me a headache. As for helmets with liners - I think Samshield works the same way too and I looooove their stuff also! Good luck!