Controversial topic, but a personal experience for both the like-minded and the not-so-much-so...
DS and I have co-slept on and off since he was an infant - sometimes more when there is emotional turmoil (i.e., when me and his dad split), sometimes just for "sleepovers" as he's got older, and recently because he was struggling to settle himself to sleep (his mind races) so I thought, hey why not try some of the meditation / mindfulness training I am currently practicing with him?
So we sleep in the same bed together, doing a guided mindfulness meditation (body scan, for those who are familiar) at bedtime and he falls asleep sometimes 30 seconds in (like the first few nights), and sometimes after 15 mins or so (more recently), which is an improvement over the 30 mins to an hour we used to spend just chatting to exhaust his mind from all he'd stored up over the day! Now he really loves the practice and craves it - he asks every night for me to put on "the guy" (it's guided by a male voice), and we listen together, and many times we both end up dropping off together.
This is the part that I love, and that's just for me - sometimes he wakes up in the night, and in his half-sleep he says "I love you mom." It's the best part of my day, and the sun hasn't even come up. Don't get me wrong, he's a loving kid, so I hear that a lot, but to hear it when he's barely conscious, and in the quiet and peace of the night, is just priceless.
I know this won't go on forever - he will grow tired of "the guy" or he'll get into another independence stage and insist on his own bed (maybe with "the guy", maybe not), but regardless I am treasuring every night I get of this experience.
Sending this into the ether for others who still enjoy their kids' cuddles through the night - just my experience, one person among many, and it's a controversial topic, but I just wanted to share.