I didn't want to do any form of sleep training, but about a month ago got exhausted and desperate, so went for NCSS. I read it, was enthused, picked some strategies and started trying. (I love her attitude, and would ideally have liked to keep co-sleeping)
I soon realised I was too tired for the "gentle" solutions to work. DS and I would wind each other up - I was so tired I would get stressed at the fifth attempt at de-latching him and putting him down awake. DH would come in and calm him, and would rock him to sleep - but no luck getting him to go off on his own - we were both too tired to have the patience. When you're so exhausted you want to scream at your baby instead of patting them, you know you can't do it.
So, as recommended by someone on here, I bought HSHHC (I was so desperate I paid 8 quid to get before 1pm the next day delivery from amazon). I read it, and hated it. Its very clinical, gives bad advice about breastfeeding, and (on first reading) seems to advocate Cry It Out as the best way to go (Later readings gave more of a "this will work best, but if you have the patience XYZ will take longer" impression).
However, the next day, I was at the end of my tether - even more tired than before. I hadn't eaten my dinner, DS would not go to sleep, or feed, or anything - he was doing his crazy wriggling monster impression. So I put him in his cot (at the side of the bed, in our room) and walked away to eat my dinner. 20 minutes later, with every mouthful having tasted like ash, DH and I went upstairs and checked on him. We decided we might as well keep going, and started doing CC - checking on him. Another 25 minutes later he was asleep, and I felt awful. I felt like I couldn't leave him to cry any more, so just fed him when he woke, and was, of course, even more tired the next day.
The next day we decided to give it another try - promising each other we'd do it properly and not feed every time he woke. With CC it took 35 minutes to go to sleep. He was still in his bedside cot, and when he woke first time in the night, DH and I got a bit of a wakeup call. DS screamed his head off. Big, loud angry screams - we knew he was angry because we were there and we weren't picking him up. I'd bet that's all he could think about!
So we both got up, out of bed and left him to it. 20 minutes later, he was asleep. Since then, he's getting better. He never cries for more than 20 minutes now - and only that much when its an intermittent cry/grumble rather than the full-on complaint. Moving him into his own room really helps.
We go back and forwards with the night sleeping / waking- backwards after I fed him several times in the night when he was teething, then was too worried to leave him cry the next night just in case he was still uncomfortable - even though he wasn't doing that sort of crying! Its taking us a while to get back from that but we're getting there.
In two weeks, we've gone from 3-10 wakings in a night, to 2-4 (he gets left for 2 of them and sends himself off to sleep pretty quickly)
Nap wise, HSHHC has helped me to think about his sleeping patterns, and I have paid much more attention to his sleep queues so DS normally feeds to sleep really quickly at nap time. We're still working on duration, but he does 2-3 naps per day even on a bad day (they just only last 35-45 minutes each and we really struggle to get him to nap until we get home)
Where is DS3 going when you're at work - surely that will have an impact on things?
Anyway, HSHHC stuff has worked better for me - I have been saying that if you've got the time and patience, I'd really try the gentler methods, but if, like me, you left it too late and can't cope with the stress of things like pu/pd or patting etc, it does seem to work.
Phew, that was long!