I have used Allisonhouse since 2010, and have been very pleased with their service. I can count on one hand how many times they were down in that time frame, and when they were down, the NWS was normally down as well. I will continue to use them for the foreseeable future.
@pertman - To my knowledge there aren't any other data services like Allisonhouse for Level 3 radar data, outside of the default NWS connection.
@WeatherHost - Back when I started with them (April 2010), the default Level 3 service was subject to overload anytime there was a severe weather outbreak (think about the nationwide 30 minute radar outage that occurred during the Yazoo City, MS EF4 tornado on April24, 2010). Granted it is far better now than it was then, it is still subject to overload.
In addition to having GR2AE/GR3 radar access and having available many placefiles that I use on my website and personally when severe weather is in my area, I can also use my subscription on Radarscope on both my phone and tablet. Plus, their customer service is top notch.
John