Hey Seebr.. I went from wearing an Arai Quantum/E for about 4 years to a Suomy Spec-1R late in the season last year. The fit for the 2 is the same for my head. They were both noisy helmets. Even though the Suomy has more vents than the Quantum/E, the noise level is about the same. They are both very comfortable helmets, but the Suomy seems a little more simplistic in nature. You have control on one vent for the Suomy, the chin vent. The other vents are fixed open. There are no visor vents on Suomy.
In a sense, I like that there is less fiddling with the Suomy. One thing that I do miss on the Arai is the pull down chin dam. I'm not sure how effective it was keeping the cold air off in the winter, but every little bit helped. Where both helmets are excellent in fit and finish, the Arai has a few more user controllable features built into it.
I'm happy with Suomy.
It would be toss up now for me between the corsair and the spec-1R extreme