I had the 14' x 26" Astro in Venice. I tried the 12'6 x 26" last week. Obviously the 14' is faster, it's a really well balanced board and runs well. There's enough rocker in the tail to kick turn with 3 strokes for 180deg, but flat enough to keep the length of the board in the water when paddling (I hate it on most inflatables where the board bananas excessively in the middle and the tail sits out of the water).
The 12'6 behaves in exactly the same way and very light....very light. Stability is good for a beginner-intermediate on the flat, but on the ocean I think a beginner would find it challenging. These boards are the new standard for race inflatables - it will be interesting to see where this board type goes.