Good Chinese SatNav Double Din Feedback?

[Cullers]

Hi
Last year I had to lose my Boxster. I had fitted an Alpine 920 double din satnav in it.
Now I am close to getting a replacement and want to get myself a good unit to put in it.
I have been looking at the Chinese units as they seem to offer a lot of options the main players don't do.
I'm hoping that some members will have feedback on the units - what is good and what is rubbish.
Main on the list are the Xtrons TD618 and TCD698 but any units I'd love to hear about.
Thanks in advance

[Cullers]

Thanks Dennis. Appreciate the advice. I've ended up getting a Clarion although on getting my car there is a Panasonic already in!