Well - after finally deciding to buy an Xtrons TD714 DD Unit and almost two years on I'm pleased to report that the unit has exceeded my expectations both in terms of its performance and the much doubted reliability factor. (or did I just happen to buy one that was made properly by a discerning and conscientious Chinaman!!)
I grafted on a JBL power amp and 12" sub unit and both work well alongside the factory fitted Bose amp and Omega standard speaker set.
The sound is clean (depending of course on the recorded quality of the source audio/video) and volume levels more than adequate for the Omega interior. The 7" display is clear and reasonably bright during normal daylight conditions and blinding (but can be adjusted) at night!!.
Touch screen and Menu controls are good although the Operating System is a little dated.
Bluetooth works well with my Android phone on both hands free calls and streaming MP3s, although a little laggy (switch over response) but acceptable when receiving a call whilst playing audio.
It has given me what I was looking for at an affordable price.
I would recommend this unit to anyone on a limited budget and it won't break your heart if it gets stolen!!,