Distance and Serial or SPI
I have a few years working with DMX, SPI (and other serial) &amp; LEDs. I have worked with DMX and a video dance floor for 10+ years previously. I would offer that "some people" are correct. You will get a reliable system with differential pair signalling (such as DMX).
I have found from experience that over 5m of unbalanced serial starts chancing it. Over 10m and you are likely to come up with at least reliability issues, but more likely garbage. 

I have used the TI SN75176B driver a fair bit and is cheap and works. 

Depends on your audience. You can afford to chance it for your bedroom, but not paid business.