So after about 50 games of ranked and playing roaming I love it.
But here are the problems. Low XP, you are never in lane for more than 3 minutes. If your team doesn't act when you do your wasting your time ganking.
Also here is my list of characters that I believe to be viable roamers.
Eve straight up harassment with stun.
Alistar stun and a knockback. He is good a little reliant on flash imo.
Janna a slow and a knock back and you make other people hit harder with your shield.
Taric Heal/Stun/Armor Debuff
Moaki Snare and kockback
Blitz Hes ok he has his pull and his knock up.... But in my opinion he needs more gold than you get with a roamer.
And that's really it for good roamers in my opinion. I am currently experimenting with Gold/10 quints and XP quints. I can't seem to decide on what I like better.
Going to go play a game with Roaming Janna and actually try her out.