Applying to jobs in multiple disciplines. How much does name of degree matter? I'm currently a second year masters student applying to PhD programs but are at a bit of a crossroads and wanted to crowd source some opinions. 

My research interests are in a subject studied significantly by people in two different disciplines (I'll call them disciplines A &amp; B). A is strictly in the physical sciences, while B is very diverse and encompasses research ranging from the physical to social sciences. There can be some differences in how each discipline approaches the subject, but frequently there isn't, and people from both generally publish in the same journals, present at the same conferences, etc. 

My bachelors is in A and I am in a B department for my masters. I really enjoy my current department, which is small but generally well regarded, and advisor, who is prominent in his field and extremely supportive. Additionally while in a different school, my current University has a world class A department with great people working in my field of interest. There is a some cross department collaboration, and I've taken classes with/have good relationships with the relevant professors in A. As a result it's very tempting to stay with my advisor in geography for the PhD, while also collaborating with people in A on research, publications, etc. 

However, when I think of future job prospects in academia I start to get worried. In my country (the US) the job market for A is alot better than B (there simply aren't as many B departments, and A departments are frequently better funded ). And ideally I would like to be able to apply to jobs in both types of departments.

My logical mind wants to say that if your research record is good, you publish in the same journals, present at the same conferences, have people in both disciplines on my committee, etc. that it shouldn't matter the actual name of the PhD. 

But I know hiring is not always logical. And I worry I will always have an uphill battle with hiring committees, compared to people with PhDs in A. And going through faculty pages for many departments I see relatively few people with PhDs in B in A departments. And most of those are people from Europe where research on the subject is far more concentrated in B departments. Conversely I see more people with PhDs in A hired by B departments.

So I'm left wondering if I would be better served leaving for a PhD program in an A department (again since my undergraduate is in A, and I have grad coursework/research experience in A , I am qualified). But that of course would mean leaving a great situation with a wonderful mentor, excellent resources, and numerous collaborators. 

I know there are potentially other routes to help when applying across disciplines (try to do a postdoc in A). 

But wanted to see what other peoples experiences applying to jobs across disciplines were, and if people with more exposure to the hiring end of things had any insight. 

Thank you!
Before I say anything else, I want to say that the answer to this can't be easily generalised and very much has to do with the particulars of your discipline(s). Mine isn't going to be like yours and without telling what A and B are, any folks here with direct experience will not be able to offer it. 

That said, I have a BA, and MPhil and a PhD in "apples" and for the past 7 years have been permanently employed by an "oranges" department". If I told you what the two subjects were you would look at me blankly as you tried to figure out how there could be any connection between the two. To say that there isn't crossover of people between the two disciplines is an understatement. That said, about 4 years ago I was offered (and turned down) a promoted position in an "apples" department ("oranges" matched the offer), I've had some "apples" departments attempt to poach me, and I'm considered an applesologist among other applesologists still, while mostly passing for an orangologist in those circles. I am now moving to another University's "oranges" department. I'm keen to stay in "oranges" as there is a lot more funding in that field and PhD students that I graduate have a much better chance of finding work than if they were in "apples". 

This is the long way to say that if your A and B are close enough that there is any crossover whatsoever amongst the faculties and researchers you are looking at, you are likely fine where you are. I've always found that what research I do and how well I do it is far more important than what discipline is printed on my degree (because seriously, the two disciplines I am set between are like apples and oranges). If your current location gives you excellent support and the opportunities you need to do excellent research, and as long as you keep your network going across both A and B, you should be fine. Generally speaking...