There was a good discussion on this topic recently.
My own opinion is that after passing the IMC you are unlikely to be either confident or safe to fly hard IMC for any length of time. You should however be quite confident climbing through an overcast, and flying in poor visibility. If you keep the skills going, and take the opportunity to fly with others with more experience, I suspect with time and perseverance there is no reason why you should not reach the skill level of an IR. As with so many things, it is not just coping when all is going well, but also when it goes wrong. Flying IMC with a vac. failure, followed by an approach down to minimums is a tough one. I suspect with a brand new IMC rating you would certainly struggle.