Disclaimer: I love my CanShack converter. It works flawlessly in my 2006 Touareg with RNS-510.
My converter took almost a month to get here and sometimes communication was reasonably responsive (1-2 days), other times my emails would go unanswered.
The guys at CanShack do some amazing work and I was excited when I saw their new video converter. It allows you to use a basic composite video back up cam with the RNS-510. So I promptly placed my order. A day or so later I received an email stating that I needed one of their can bus converters for the video converter to work. I replied stating that I had one installed already. The replied that I would need to send it back to them for a software update. I replied that I didn't want to be without my RNS for that amount of time. I suggested a few other options, even willing to pay for a new one if they would refund my money when they received the 'old' one. That was the last I heard from them. I sent emails and support tickets for almost 2 months. I finally opened a ticket with PayPal for a refund. PayPal did an 'investigation' and never heard from anyone at CanShack.
It's too bad, because they do great work that I don't think anyone else has been able to match. Even with the negative experience I've had, I have been thinking about buying a new can bus converter and the new video converter from them, then trying to sell my lightly used can converter on here or ebay.