When I was getting back into the purebred cattle business in the mid 90's, Maines were the list of breeds that I considered. Though there are some good Maines that work well in the commercial industry, I was turned off by the fact that the majority of Maine breeders are more concerned with fancy, clubby, show-type cattle than they are about producing good, functional breeding stock for the commercial industry. What really strikes me funny is when Maine (as well as Shorthorn and Chi breeders) are promoting that their cattle produce lots of hair. The only commercial producers that may feel this is a benefit are the guys running cows in the higher elevations of Montana, Utah, etc.
Like many of the other continental breeds Maines gained a reputation in the 70's and 80's for siring big calves at birth, resulting in a high incidence of calving difficulties. Some of the continental breeds (like Simmy's and Gelbviehs) dealt with the problem head on and have improved on their caling ease significantly. I am not aware that the Maine breed has made this a priority over the past several years, and thus may still have a reputation for hard calving cattle.