I just did a fresh install of LMDE on my box and have had problems updating it, so late in the development cycle (700+ pkgs to update). MY ISP limits my bandwidth except between midnight and 6 am so I tried to do it with an "at" command using apt-get update and apt-get dist-upgrade with the -y option. Twice this resulted in an unbootable system so I tried the Mint Update utility and while it didn't bork anything, it didn't do the job either...lots of errors...never finished.
Going back to my past sidux experience, I thought of "smxi", the update script from H2 that was originally developed for the transition from Kanotix to sidux and has grown up since (http://www.smxi.org). It is a hands-on/command-line process with some decision making required as you go along but the result was just right...a fully updated system working great! CAUTION: It will work for LMDE but not for any Ubuntu based Mint distros!!! It isn't for the Linux noob but it doesn't require a geek to drive it either and the many options it offers are worth exploring. Smxi also includes the means to upgrade your graphics driver easily and even gives you a lot of options for kernel upgrades that I didn't pursue this time.
One of the many nice things smxi does is give you a lot of options for installing neat stuff...one of the best being "ceni", a command line utility for setting up your network cards (also developed originally for sidux). Ceni beats Network manager cold, giving you complete control over all your network parameters (or dhcp automation...your choice!) in a nice, text-mode graphics format.