I bought a JXD 7800B last year. After some firmware refinements by third parties, it became a wonderful device. This year I bought a 7300C as a secondary unit, also with it's own 64GB micro SD card.
What a horrible device. It is most definitely the worst piece of tech I have owned in my 39 years. There was nothing I could do to increase performance. As in, it really needed a decent firmware. No one seems to have really bought it, and the fact that the case has an Ice Cream Sandwich android on it shows that JXD really only released this item to the public to get rid of surplus parts.
It was in my backpack on Wednesday and received a shattered screen. I was resigned before this to use it just as an XBMC (now renamed, 'Kodi') player to hook up to my TV via a mini HDMI cable I bought for 8 bucks from dx.com ...
It couldn't pull its own weight, which is sad to acknowledge due to its decent specs. It cost more than an Amazon Fire, or MINIX box, and was 100% a waste of money.
If you are considering buying one, don't. Instead save your money a little further for a 7800B. I guarantee you the money spent will save you a slew of headaches.