I am about to give you advice that you didn't ask for, but I sincerely hope you will consider.
Working in a setting that does approx. 400 deliveries/year will significantly limit your practical, hands-on learning experience, necessitating a very lengthy orientation (probably more than 6 months) in order for you to have the opportunity to develop a knowledge base, skill set, organizational skills, proficiency in emergencies, etc. With 400 deliveries per year, your facility will do roughly 1 delivery per day. Assuming that you will work a 40 hour week, it is not likely that you will be present for more than 2 births per week. At that pace, it will take a LOONNG time to become an expert care-giver. If you choose to work in this facility, PLEASE insist on a written plan of orientation that is sufficient in length, and the presence of sufficient experienced staff members to facilitate your learning and patient safety.
In the tertiary care setting, you will see and do more in terms of advanced skills in a few months than you would in years at the birth center. Please don't misunderstand me, I'm not bashing the birth center environment (I desperately wanted to deliver in one myself!) But RNs who staff such centers MUST be highly skilled and experienced because of the lack of immediate resources when complications occur. Most centers recruit experienced nurses who are ready to move to a lower-intervention setting, and most have experienced nurses knocking down their doors for positions.
I spent most of my career in the NICU, which I see as similar to L&D in many respects. I found it ideal for new grads and nurses new to the NICU to work in a tertiary care setting for at least a year or two before moving to Level II NICU's, whose patient populations usually do not support an adequate orientation for a newbie.
Good luck on your decision.