Have just converted from sliding to French doors. So much better!
Get a wind restrainer on the door or the wind could take it. Lets loads of light and air in. A lot more secure as well. Go for the French doors. I didn't have any replastering to do, the door fitters just tidied up the rough edges, just a little paint was all the walls required. Its not a big job, they had the old door our and the new one in, in about an hour and a half.