Take the job, the job market at the moment is not the best. Plus from what I understand they are offering you, you will get the chance to write papers, and even a funding proposal. It will be the first step on the ladder as a lot of employers will prefer to take on someone with actual experience. If you take the job and do not like it you can even continue to look for other jobs whilst working. It is an opportunity that you should not pass up as there are a lot of others who have graduated from there PhD who will not think twice about saying yes.:-)