Don't worry about the gear until you are fully competent with lesser quality tools and what you already possess. A shit story captured without lights, with awful sound, on a several hundred to several hundred thousand dollar camera will still be a shit story.
In other words, you should focus on learning to crawl before you try to compete in an olympic running event.
That said, I don't agree necessarily with the negative feedback about the Black Magic 4k. I own one, and it's got a really nice image. Details are escaping me at the moment, but I seem to recall hearing about a feature in production that's using the 4k, recently.
4K won't go away any time soon.. HD took quite a while to catch on, and while it's now more or less considered 'standard' I guarantee you there are still a great number of people who don't have HD televisions. The vast majority of cable and satellite networks are still delivered in standard definition. 4K TV's aren't going to start selling like the best thing since sliced bread on a wide scale any time real soon.. it's just not realistic.
At this point, nobody really NEEDS 4K, unless, perhaps, they are doing a lot of high-end VFX work and really need the extra resolution.
Also, keep in mind, that while the price of the Black Magic 4K (now on sale for $500 off) is about $3000, you also need a bunch of additional gear to make it really useful. You need an external battery solution, you need lenses, you need IR and ND filters, you need some form of external monitoring solution (the built in screen is nigh unusable in bright daylight, with it's mirror-like finish).. realistically you're probably looking at a minimum of another $3000-5000 in accessories and whatnot. So suddenly that great deal $3000 camera is going to run you upwards of $5000-10,000.. still, a pretty great deal for what it offers. But if you're lacking experience in general there's absolutely no reason to sink that kind of money into gear, and while you may _think_ your computer is capable, it's almost certainly not.
That's just covering the camera.. of course without great light you might as well be shooting pixelvision. Without great sound, you might as well just not bother at all.. and without a story worth telling, there's no point to even think about any of it in the first place.
Yes, the black magic 4k is a great little camera, especially for the price point it sells at. But unless you've got the means to provide it with the necessary accessories, camera support, and the like.. don't bother.