When buying multiple cameras there are two key ways to look at it:

Complementary cameras or matching cameras.

In some cases you want your cameras to be “matching cameras”, such as when doing multi camera coverage of wedding ceremony or doing an interview. Such as 2x GH4 to cover the wide of the interview and the close up, or one to cover the interviewer himself and another on the person being interviewed.

But in most cases you want your cameras to be complementary instead. As you need to view each camera body as merely one kind of tool in your box of tricks. So when you go out on a shoot, you can pick the best tool for the job.

Thus for cameras to be complementary, you want one camera to cover the weaknesses of the other, and in the reverse too.

For instance GH4 + BMPCC:

96fps vs 30fps
Compressed vs raw
Photos vs n/a
4K vs 1080

Or A7s vs BMPCC:

FF vs S16
Amazing low light vs so so low light
Compress vs raw

You can see how in each case, one does well in covering some of the weaknesses of the other camera.

Thus you can see how for many people getting a BMCC and BMPCC makes no sense at all really, as they’re two very similar cameras.
So this BMCC + BMPCC combo only makes sense if you’re looking for two “matching cameras” rather than two “complementary cameras”, or if you already have a BMCC and you want the BMPCC to just cover for the big weakness of the BMCC: its bulky size.

I really wouldn’t recommend the BMPC4K at the moment, URSA Mini 4K is just around the corner for the same price and is better in every way.

What I’d suggest is getting a Samsung NX1 right now (or any one of the currently top three hybrid cameras: Samsung NX1 / Sony A7s / Panasonic GH4. But I reckon the NX1 is the best of the 3 at the moment) and a set of Nikon F mount lenses. Then when the USRA Mini ships (and “if” it gets the favorable reviews we’re all expecting) get that as well. You’ll have a killer combo of two cameras able to cover a wide range of needs. Don’t worry that the URSA Mini is still a few months away from shipping, as having the Samsung NX1 to start with is still a phenomenal camera, and when you’re just starting out your equipment really isn’t your limiting factor just yet. As gear has got so good and so affordable.

If you lean towards doing a lot more multi camera work (such as weddings) than single camera, then I’d suggest instead starting out with a Panasonic GH4 for you, plus Panasonic G7 for your second shooter (your second shooter might supply their own camera, but even if they do, it is best if their camera matches well with your own. Makes life easier in post), and 3x Panasonic GH1 bodies (which go for merely US$150 on eBay, and still are quite damn fine cameras! Does miles better than any Canon Rebel series DSLR shoots) to cover the multiple extra angles during the ceremony and speeches. Then once they ship, pick up a BMMCC and BMD VA for your single camera work (music videos / adverts / short films / etc). Or get a BMPCC if you simply can’t wait for that.

I wrote this post in response to this thread on bmcuser, and felt like sharing it as a blog post too because my response is length yet generic enough it might be helpful for others too looking at getting more than one camera.