Hi I can`t comment on the Tribal 2 as have never flown one, however I have had a 12 m Atom for a few months and I really rate this kite highly for my ability ( 2nd year kite surfing, and several years flying land kites ).It`s very easy to set up, has a simple and safe quick release system and so far has stood up to a bit of abuse and seems very well made. It`s very user friendly and has enabled me to take my kitesurfing to a better level over the winter months. The depower is excellent and the performance is great aswell, big floaty jumps etc. I`ve found it very good in the gusty and choppy south coast conditions we get down here. I think that you would be very happy with it for the freeride 15-30mph range that you wrote as this is pretty much similar to my requirements.
There are 2 "bad" points that I have found. Firstly, the depower strap is too far away to reach comfortably, and secondly it can take a while to get it to re-launch from the water sometimes. However these are irritations more than anything and in summary a great kite and in my opinion I would definitely recommend it.