Sleep separate. We are on baby #2 and #1 slept in our bed for almost 12 mos. It was terrible as the baby got bigger an would move around. No one got sleep. Sleep deprivation is bad for parenting and marriages. If you knew your child's school bus driver was operating on 3-4 hours sleep you'd pitch a fit, why should parents do the same?
#2 is sleeping in her room in crib and we have a twin bed in that room and we take turns sleeping in that room with her. She starting to stay asleep at night for longer periods and is almost 6 mos old. She also has terrible reflux since she was born and would vomit up even breastmilk so she is on a special formula.
My experience is that sleeping together makes things easier at the beginning when it does calm them but it's harder to break it the later you leave it so you're just trading off early pain for later pain. We took the pain early and it's worked out well enough that we'll likely do the same the next time round.
Our experience was great. She slept with us for a month or so (breastfeeding). Then we felt we'd sleep a little better if we put her in her own bed right next to us, so we did that (in the same room) for a few months. Being in the same room makes it easier because you don't have to go check on her in another room. Then at 6 months or so we put her in her own room. It all went totally smooth.
Don't be afraid to sleep with the baby if you feel like it, and don't be afraid to put them in their own bed if you feel like it. It's ok. Also, putting them in their own bed in the same room for a little while gives you a lot of advantages (easy to check on them without getting out of bed etc.)
Basically, just do what you feel like and if it isn't working try something else.
We didn't have early or late pain. Our older son was an epic sleeper, our younger son not so much; but each of them decided in turn that they wanted to move into their own room, which we happily obliged.
#2 is sleeping in her room in crib and we have a twin bed in that room and we take turns sleeping in that room with her. She starting to stay asleep at night for longer periods and is almost 6 mos old. She also has terrible reflux since she was born and would vomit up even breastmilk so she is on a special formula.