Both are good units that are sold by reputable companies.
We offer the MDC unit and as the supplier of the MDC unit we feel it has some advantages over the Area 451.
The advantages are:
Simpler installation
No need to modify or splice any wires
Built In Sprint Booster module (a comparable feature in a stand alone unit sell for over $300)
The MDC unit has and continues to be installed in more smart cars across the world
A direct plug in LED included at No Charge
Here is what is comes down to... Most of the folks that own the Area 451 unit (more of them on this board since the Area 451 unit was sold to members on this board for a longer period of time than the MDC unit. The opposite is true in the EU.) love it and will swear by it. Most folks that own the MDC unit will say the same about theirs.
Steven is a great guy (owner of Area 451). I have spoken to him at times and cannot say anything but good things about him and his business practices. As the owner (me and Rachel) of Smart Madness I hope that people say the same about our customer service and our business practices.
Both units are great and they both make a good addition to your smart car. If we can ever be of service or answer any questions please do not hesitate to call us at 562-961-6800. We are open 10-6 Pacific (Tue-Fri) and 10-4 on Sat.
If you would like to see more info on the product here are the direct product links:
smart car Cruise Control w/LED by MDC - Cabrio model
smart car Cruise Control w/LED by MDC - Coupe
Thank you,
Boris