I got back from doing a similar trip yesterday – did the long loop at N-y-A, which takes in all the best bits of the two shorter trails, coupled with some crazy double-track,loose-slatey descents (huge ding in my shiny new Trance frame), in some spectacular scenery – it’s worth doing and don’t let anyone tell you otherwise! We camped at Woodlands campsite, Devil’s Bridge just down the road – highly recommended (decent food and lunatic cider at the Hafod Hotel 5 mins walk from the campsite). We drove down to Brechfa yesterday morning in about 1.5 hours – I’d never been before and loved it. Have fun!
With Brechfa, unless I missed something, the black seems to be an optional extension at the top of the final descent of the red trail. We didnt bother, as popular opinion appears to favour the red. Plus, talking to two riders at the car park, they mentioned a section was closed atm..