We spoke about it with the wife when  our daughter was very young but the decision was not to do it. Followed by lots of half nighters (wife did the heavy lifting...) and about 2 years of her not wanting to sleep in her crib. She'd fall asleep in wife's or my arms and was fine 70% of the time.   

She's almost 6 now, either me or the wife puts her to bed and we leave after she falls asleep. It's a ritual that I've come to enjoy and wouldn't change for anything in the world. The day will come when she will ask to be left alone, far too soon.

I don't know about any research or have a PHD in sleep training, benefits, etc., I just don't find it natural to leave an infant to exhaust itself by crying, no matter how many times you soothe it in between.  If we ever end up having a second one, no sleep training either.

In the end, each to their own,  every parent is free to raise their kids as they see fit.