Your toughness is made up of equal parts persistence and experience. You don't so much outrun your opponents as outlast and outsmart them, and the toughest opponent of all is the one inside your head." - Joe Henderson
DNF as in did not finish (just me playing devils advocate) I've actually known quite a few who have trained hard for a race and ended up not being able to finish it (not implying that will happen to you).
It's nice to be able to do a race with someone. I'm the long distance runner in the family and dh is the sprinter. We've ran almost every race together (except a few 5k's and one 10miler) Of course I told dh this next marathon I'm not waiting for him ( I'd really like to see what I can do myself).
You'll ruin your knees!
""...the truth that someday, you will go for your last run. But not today—today you got to run." - Matt Crownover (after Western States)
Just Do It ... and Enjoy It, ...if there comes a point when you're suffering just look around you, and then look behind you...watching everybody suffering but determined to keep going got me to keep trucking along..
Would you recommend 12-14 the week before?
"Able to function despite imminent catastrophe"
"To obtain the air that angels breathe you must come to Tahoe"--Mark Twain
"The most common question from potential entrants is 'I do not know if I can do this' to which I usually answer, 'that's the whole point'.--Paul Charteris, Tarawera Ultramarathon RD.
√ Tahoe Rim Trail 100M 19/20 July 2014
Georgia Death Race 14 March 2015
Boston Marathon 20 April 2015
Do it. I've never regretted jumping into a race. Even when it took me two hours to jog/walk/crawl the last six miles of a 50k. In fact, that turned out to be one of my most memorable races--and made me go back and do it right. Injuries heal. Glory is forever.