Hi All...newb here with a question on helmets. Are there any negatives to buying a helmet with a removable visor? I've read that road helmets are without them and mtb helmets have them. I've also read many road and mountain bike helmets are identical but sold under different names, the only difference being the addition of a visor (ex. Bell Alchera/Delirium). I currently ride a 1995 Trek 850, primarily on a vast network of paved park trails near my home. As I've begun to ride more, I've felt the need to get a helmet but I'm not sure I might not want to get a road bike and hit the highways, so I'm looking for a helmet to serve both purposes. Helmets that offer removable visors seem like a no-brainer to me...so being a newb, please tell me if I am missing something...thanks in advance...