For my first touring type sea kayak I set criteria of: light weight so I could load it solo more easily, hence kevlar; length 15-16 feet, to fit in my garage and short roof rack; stable but good handling hull design; rudder with fixed footpegs. My web searching revealed only one boat that seemed to meet these criteria. This was the Q400X in Kevlar/Carbon layup with SmartTrack rudder. I ordered one sight unseen on the basis of the good owners' comments, the good impression from their website, and the description of the hull design that maximizes waterline length, which seemed important given the short 15 ft length overall.
Here are my impressions after 3 months of ownership with day trips in coastal BC. I am male, 5 ft 10, 160 lbs, age 66, Level I skill.
The boat feels very stable, as good as anything I had rented previously and better than most. Tracking is impressively good for the length - with the rudder up I have no difficulty keeping a straight course without weaving. In spite of the high deck profile, it seems not to have weathercocking problems at least in the moderate wind conditions I have been in - people in longer and lower kayaks were complaining when I had no problem. It seems fast for its length as I have had no trouble keeping up with the group - the waterline length is actually longer than any other kayak in the group up to 17 ft. overall length. I have not had it out in wind waves higher than 1.5 feet and it did OK but was showing some 'slapping' when the other traditional sloped bow kayaks around me were cutting through, so I am waiting to see what happens when I hit larger waves. (Whether that 18 inches of sloping bow of the other kayaks has an advantage in waves remains to be seen.)
The cockpit is quite wide, probably too wide for my narrow body, but certainly easy to enter. My legs are long for my body, and there is plenty of length to the footpegs, so the Q400X should be good for a person over 6 foot and considerably heavier. The downside of the long cockpit is that the forward bulkhead placement reduces potential forward stowage volume. There is no lateral thigh support. The optional thigh braces only provide a wider horizontal lip. So far I have not found this to be a problem as I can exert enough vertical pressure to keep from sliding horizontally, but possibly some modification may be desirable in the future.
I have not been able to weigh the kayak, but helping to carry other boats in our group shows quite clearly that my Q400X kevlar/carbon, while lighter than any of the fiberglass boats, is heavier than any other kevlar boat that I have helped carry, including 17 footers. Part of the weight is likely due to the high sides and domed foredeck - there is simply more area of composite for its length than lower boats. However, I think other new boats likely have more advanced construction methods to reduce weight. Still, it is a relatively light boat.
My main disappointment with my Q400X is with the construction quality control. It looks very nice externally and the deck fittings are high quality, but the underdeck finish is really very poor. The interiors of all brands of kayaks in my local showroom are far better looking. The QCC looks non-professional in contrast. In particular, the sealing of the bulkheads was not only aesthetically ugly but allowed for fairly serious leaks into both the forward and aft compartments. There was also a minor leak along the deck seal line. I sealed all of these myself with 3M 5200 marine sealant. The bulkhead seams are now even more ugly, but do not leak. This only cost an hour or so of time and $20, but should not be needed on a new boat. Another problem was that the forward deck perimeter lines were cut too short so that one side could not even go under one of the fittings and the knots had no free line at all so that I was concerned that they would work loose and if they did it would be impossible to retie them. This was a safety concern. I replaced the line with the reflective type. Again, this was relatively inexpensive to do, but should not be needed.
I have not yet measured the volume of the storage compartments - QCC gives no specs - but it seems to be large for the length. I hope to go camping this summer with it. I have no experience of how it handles loaded with gear.
I did rolling and edging classes in a pool with this boat. On edging it is stable to slightly more than 90 degrees on its side (slightly beyond being right on its side) with no change in feel - a very pleasant surprise to me. I am still learning to roll, but my initial impression was that the high deck and wide width were not presenting a problem, when I managed the right technique, I came up. However, in the abstract, a narrower and lower deck boat would seem to me likely to be easier to roll - more experienced people can advise on this.
The hull design is clearly unlike any of the other boats owned by people I have paddled with. It does "look odd" when surrounded by the sleeker designs. It looks "big" in spite of always being the shortest one (length over all) in the group. This design does seem to offer some functional advantages, but it does stand out. I don't mind this myself being more functionally than stylistically biased (an ex-engineer you see) but others may feel differently.
So overall, I am pleased with the boat. I will try to update this review when I have had more experience with it.