Both CC units seem to be of a quality so whichever one is chosen will not be an issue. Those that have the MDC are happy, those like me who have the 451 are happy. All is good when there are two quality vendors. Competition keeps prices down and quality up.
For those that asked about the LED in the instrument cluster, I bought mine from John. He offers them in different colors and sells a kit complete with a 9v battery to test it. I got the blue one and absolutely love it. Unless the sun is directly on the dash, it can be seen very easily. The LED gets installed on the upper right side of the instrument cluster. I installed it myself in about 1.5 hours. I went very slowly to ensure I didn't splice the wrong wire or pull something apart that shouldn't be disassembled.
Who would have thought the instrument cluster would have an unused CC indicator. I guess smart thought about installing CC but decided against it at some point.
John takes PayPal. My receipt has two e-mail addresses on it. firstname.lastname@example.org and email@example.com
John is a smart owner and if I recall correctly an electrical engineer who wanted an LED CC indicator for himself. He isn't trying to turn a huge profit, but does enjoy helping other smart owners. I think he was asking 20 bucks but I sent him $30. While the parts may be inexpensive for $20 you still get the LED, wire, parts, (tools and battery if requested) and also shipping. It had to take him a while to develop the product as well. To me he's $20 is a bargain. There is also an install video you can view on line and/or download.
Unless John started up a website after I bought mine, I don't think he has one. I tried to upload the video to a prior post but it was way too large and my post crashed. I did attach a sheet I made up which is a compilation of things read on the net and from John. In it are links to a 451 discussion board that if memory serves has the video. There was a 20 second or so glitch in the one I had anyway so maybe it has been edited and improved. My prior post also has a couple of e-mail address you can try to contact him at.