I've been using there 4th gen since it came out and its money well spent. I haven't used the Boss TV box but have seen demos of it in the shops in SSP, and I think its geared more to the Mainland Chinese, whilst the marketing of the UBTV (from their FB page) seems to cover more of SE Asia.
I've actually found their servers to have been more stable since the turn of the year, I used to never be able to stream the UK channels such as ITV or BBC2 (BBC1 was always fine), but they now stream OK. Same goes for the UK sports channels I watch (BT Sports 1, BT Sports 2 and SkySports 1), they used to be jittery once every other connection, but most times now they stream jitter free.