I don't have much to add to the excellent comments above, so I will make some general comments:
1) Pay - it can vary wildly; for those willing to answer from my class, the range was $150 - $325K/year. The low end was for someone who essentially felt locked into a certain geographical area and HAD to take what was offered. "They" knew it and lowballed her.
I make more than the average general surgeon, take no general surgery call and in a year in practice have very, very rarely gotten a call afterhours or on the weekend which required me to do anything more than give advice/order over the phone. As a matter of fact, I am trying to remember if I ever have.
At any rate, like most things, your pay will depend on your negotiating skills and your flexibility. I was able to say *&*^ you to people who lowballed me because I had no geographical restrictions (other than I wanted to be in a big city and be warm).
PP will pay more, in most cases, than university hospitals. Many community breast centers want a fellowship trained breast surgeon to be their medical director and you can be handsomely rewarded for this.
The key, as noted above, is volume. And the key to volume is efficiency. We don't learn this in residency. I have learned to try and book my cases at the hospitals where the turn over time is short, where I have less paperwork to fill out, where the staff is motivated and the drive there is shorter. I can do 10 cases in a day if everything flows smoothly. Don't believe your academic surgeons who tell you you can't make money doing breast...I was told the same story by my faculty. They have the academic mindset in which they have no motivation to do 10 cases a day and don't do image guided biopsies.
2) Image guided biopsies...I make more doing an ultrasound guided biopsy in the office than I do a mastectomy; I could do one of the former in less than 1/5 of the time of the latter all without leaving the office.
Even better is placement of brachytherapy catheters. Some surgeons don't place these in the office but rather do it in the operating room. Money left on the table as you lose the facility fee. I have 3 of these scheduled for December 2. I will make more in that one day than I made my entire first month in practice by doing that procedure.
Needless to say this is an important skill to have and should be heavily weighted in your choice of a fellowship if you aren't interested in academics. You must also assess the local environment; some communities are heavily radiology influenced and you will have a had time getting your foot into the door to do the biopsies. My area was great; the surgeons had set a precedence for doing them.
3) Gender - it is true that some patients will prefer females. But most breast surgeons are still male and while you may miss out on some referrals if there is a female surgeon close by, if you market yourself and take good care of patients you will probably do well.
4) Call - Very few breast fellowship trained surgeons want to take general surgery call. droliver notes that this is a problem at some hospitals and this is true. I know one of the local hospitals here where I'd planned on getting privileges changed their bylaws to require all general surgery trained surgeons to take call. A bit disappointing but frankly I'm in a large city and there are tons of other hospitals that don't require it.
One must be careful when interviewing for a job to assess this issue if its of importance to you. A practice has no control over what local hospitals require. So just because you may be hired without having to take general surgery call, if you can't find a local hospital that will give you privileges without taking it, then you are SOL. Thus, make sure when considering a PP or community practice that you assess the local temperment and requirements before signing. For me, GS call was a "walk away" point in contract negotiations and jobs that couldn't guarantee it, fell off my list.
Needless to say, I think its a great field - great patients, lots of face to face time with them, multidisciplinary and lots of work without the lifestyle issues of surg onc.
However, the patients are very very needy. Missing a breast cancer is the number #1 reason for malpractice suits so everyone is on edge. Breast patients will sue you; your Whipple patients won't. You have to slog through the inevitable breast pain and the patients with normal clinical and radiologic exams because someone "wanted to be sure" or didn't know what normal was. It can be hard to have a cancer only practice when you start - you have to take everything.
I agree that you shouldn't do a surg onc fellowship if you are only planning on doing breast; most surg onc programs include on 6-8 weeks total on breast. Its highly academic of course. It WOULD give you more options if you changed your mind during training.
At any rate, this is pretty rambling...darn lifestyle specialty, I haven't been home before 800 pm once this week, so I'm tired.