In short:
550/325: Freeride/freestyle, Big waves/huge speed range
548/325: High lift/low wind/early planning, mushy waves, slow speed, white water+bubbles. It has about half to one kite size on the 550. Not only for beginners.
More details:
The 550/325 combo was called the wave setup last year. It has been by far my favorite and was extremely happy to see that Moses decided to make it the workhorse for the 2017 lineup. The beauty of the 550/325 combo is the range: it is stabile between 7-30knots, with no tendency for ventilation or cavitation. It is very agile and responsive. I am loving it for wave riding and helped me a lot when the winds were out of control. I used the 550 in overhead waves riding strapless. Winds were up to 30knots and I was powered/slightly overpowered on my 5m Voyager3. The most important attribute of the 550 compared to the 548 that it can take a lot of speed. When sliding down on 9 feet steep faces and kitelooping at 30knots wind the foil is going to accelerate and reach high speed. So, it is crucial that it does not have a tendency to cavitate or ventilate. There was lots of seaweed which made the obstacle course even harder. The 550, however, did an excellent job: effortless and agile on the faces and stabile even when pushed to extreme speeds.
548: not only for beginners
The 548 is part of Moses' beginner kit, the Easy 41, however, it is not only for beginners:) After the high winds diminished and the waves reduced to mushy 2-4' it was time to switch from my 7m to 9m. Instead I decided to swap the 550 for the 548 and gave the 7m another shot. It actually worked out great as "being underpowered and ready get a larger kite" changed to plenty of power on it. The 548 was also significantly more stabile and ate the white wash and all the bubbles with superb efficiency. The 548 was developed to be an easy entry level front wing with slow speeds in mind. It works great under 17knots. Over that speed it is not going to ride as smooth as the 550. However, in the mushy, whitewashed conditions works as a champ and makes the crossing on bubbly waters easy.
548 combined with the 71cm mast: the musher machine for inside the sandbar ride
Conclusion: differences are unexpectedly huge compared to the 2mm cord lengths (548 vs 550)! A lot went into the design of these shapes. Ride can be customized according to styles and conditions.
You can find more info on this and on hydrofoil gear at
www.kitehydrofoilmiami.com