I have used L&M 3 times in the past and will use them again in December. They have always given me great service and there's never a line at check in. There have been reports in the past of bad service but I haven't read anything recently. And some people who report the bad service have never personally dealt with L&M but are just relating stories they heard.
If you don't want to buy the extra insurance, bring a copy of the front page of your car insurance with you. I know where you can get a coupon for a free upgrade, email me if you need one.