What is the difference between the Helios & the Sunny?
The Helios II and the Sunny are very similar in dimension. We typically recommend the Sunny for those people who want to paddle most of the time solo and occasionally double. This is because the Sunny seats can be setup so a solo paddler sits in the middle of the kayak, thus balancing the boat in a crosswind.
The Helios II is a somewhat better double kayak than the Sunny. This is because the Helios has more spray protection for the paddler in the front cockpit and because the optional rudder for the Helios provides better control for double paddling than does the fixed skeg of the Sunny. So pick the Helios II if you plan to paddle most of the time double.