I've just done sleep training with 'rapid return' philosophy for my 2.5 year old and after hell on earth for a month, he has started sleeping through...DS really is very stubborn and wilful but we got there in the end....For DS it was fairly painless process, no crying etc, just hard on the parent iykwim.
Before we did it, we had to let him dig his nails into our elbows if we wanted him to go to sleep and bite our arms (!). He would sleep a max 5 hours and sometimes wake 6 times a night. We'd start off in our own beds and then do musical beds all night. I was always covered in scratches and bite marks from our sleep battles.
DS generally sleeps through every other night now, in his own bed, in his own room, and when he does get up, I pop him back into bed and he goes off to sleep straight away. The sleep training really does help - but you have to be prepared to see it through....and in the short term its incredibly exhausting. I still have a 5am wake up call, "morning mummy, wakey wakey, cheerios please", but DS sleeping from 7pm or 8pm until 5am straight through is a great improvement on how things were. You have to think of it as a bit more short term pain, with sleep as your reward.
Here's the lady's website that I used - she's lovely:
www.childsleepsolutions.co.uk/about-us/
Good luck with getting some sleep...