Okay, I'll add my opinion.
I purchased an SBS-1 in June 2007, and initially was delighted with it. It then emerged that I'd been misled by Kinetic into believing that MapModeS would be delivered very soon. I asked questions about this on the Kinetic forums, and got told to stop moaning about it. Other members asked for me to be banned, etc..... I even took the case to the ASA (
http://www.kinetic-avionics.co.uk/forums/viewtopic.php?t=7059 ), who admonished Kinetic about their advertising, and the ASA were assured by Kinetic that they would change their advertising. Of course they didn't, and Kinetic still advertise MapModeS as a feature of the SBS-1. It's not.
Anyway, I perservered with my SBS-1, and started using all the addons necessary to get the best out of the SBS-1 - Planeplotter, FD6, GAS Populate, BS Alert, sbsplotter, etc...... But this became a real pain to fire-up all these addons everytime I started Basestation.
Also in June 2007, Airnav offered to take a pre-order from me for a Radarbox, but at the time I decided to go with the SBS-1 instead, as the Airnav product was un-proven. That was the most expensive mistake I made.
Anyway, in February this year I sold my SBS-1 and bought a Radarbox. For me, the main advantages the Radarbox have are:
1. It gets aircraft details, photos, routes, etc. automatically from Airnav servers, so no addons needed.
2. The Airnav network has up to 1000 aircraft being shared on it, so I can see aircraft flying around the world.
3. Airnav support is the best.
To provide balance, the SBS-1 has the following advantage - it's £20 cheaper. I can't honestly think of any other advantage.