I co-slept with my premature twin sons till they were 5 yrs old and b/fed till they were 28 months. The plus side of this was that I was right there immediately they woke/ wanted feeding, cuddling/felt scared - and so were less likely to wake the other baby. They happily stopped b/feeding -going 'cold turkey' at 28 mnths and happily transitioned to each in his own room and bed at age 5 - with no difficulty at all re. bedtimes ever. I also 'believed' that I was doing something good for them, what was natural and that this was how to be as a mother. We slept on a double and single mattress all pushed together on the floor (single mum from start, so no partner BTW, so no issues with him wanting babies elsewhere). Never bought a cot at all.
The down side was that I didn't ever sleep for more than 25 mins at a stretch, myself, for at least their first 3.5 YEARS, was massively sleep deprived for yrs and yrs, so that my memory of their infancy is compromised, as it was all a daze really. Sleep deprivation meant that I couldn't actively enjoy time with my babies. It was just excruciatingly hard work.
In retrospect, I'd still probably have co-slept for about their first 1 to 2 yrs or at least had a sleeping 'set up' where, if they were disturbed in the night without me, I could just go in and lie beside them and hold them close and then sleep a bit myself, rather than having to stand or sit beside a cot. I would have balanced my own needs more and not just believed that martyring myself for them was a good thing. I'd have had more pleasure from them if they'd slept longer, alone both at the same time. But I'll never know if their sleeping might have evn been worse without co-sleeping - or better.
I really think you do what feels right for you and works for you, certainly after the first 6 months or so. I was an ardent Attachment Parenting/LLL/Continuum Concept follower. I still feel that a lot of that stuff is right and good but needs to be tempered with what actually works for each individual baby and parent/s and family set-up, otherwise it won't work anyway.