For me, using one's legs to maintain a grapple would probably be a -2 to Grapple checks, -2 (i.e. 2 better than otherwise) to main hand actions situation. I don't like telling a player, "you can do that but it doesn't mean anything".
OK, that's not entirely true. For example, when players want to drag me away from the table, or corner me at a party, to talk about their character's plans for interior decorating, I love telling them, "sure, sure, your character has a sweet pad, I'm off to talk to somebody else now!"
OK, that's not entirely true. For example, when players want to drag me away from the table, or corner me at a party, to talk about their character's plans for interior decorating, I love telling them, "sure, sure, your character has a sweet pad, I'm off to talk to somebody else now!"