Solo I had a large dog and some gear up front, which kept us in trim, and it was still very efficient paddling. The supplied seats work well for back support, but the butt seat pad is small. Hence a 9, instead of a 10.
The low profile of the TriYak does not catch the wind, and makes day trips a reality and a good time experience. Highly recommended.
Having said this let me get on to the positives about the tri-yak. Stability is excellent (primary and secondary), don't know if you'll find a more stable one. Tracking is good, nothing a few corrective strokes won't fix and this thing at over 14' maneuvers (without a rudder mind you) as well as my Tarpon 120 (12 footer).
This kayak is listed as a recreational kayak and it serves that purpose very well. I can tell a marked difference paddling it with three people (even if it is my 11 and 9 year old daughters with me) over just two of us (both adults). It shines in this area. I've even fished off it solo and duo with no probs. The seats with the pockets on the back are great, wish all other kayak companies would stand up and take notice about them. They are low enough to fit below any pfd's and still offer great lower back support and comfort for your buns.
If you want something recreational/leisure for day trips with room for three, get this yak. If you are looking for something more performance oriented (more speed and storage for longer trips), I don't think this is the kayak for you (I got my new T160i for this :-D ).
My experience is as follows. The boat was stable enough that I was able to step into it from a dock deck about 12" above the kayak. While a bratty 4 year old stated that I was going to fall in, everyone else soon stopped watching--it's that stable.
I paddled myself from the middle position and enjoyed the large smile on my face because this yak is fast enough to satisfy me. I'll be able to paddle for long periods of time at trolling speeds (4-5 mph) that interest salt water fish, and at speeds (1-2 mph) that work well for fresh water fish...well, nearly forever.
The middle seat is infinitely adjustable due to the adjustable backrest. There are 2 built in foot chocks. I think people from 4'10" to 6'8" will find a suitable fit.
I then talked the 6 year old nephew and that bratty 4 year old into a ride and was once again pleased with how well the kayak handled. The front & rear seats have multiple foot chocks in addition to the adjustability of the backrest.
I haven't raced canoes or kayaks since 1982 so it was with some apprehension that I ordered a Try-Yak. FeelFree Kayaks didn't exist when I was involved and they don't have a world class paddler like Greg Barton (Ocean Kayak) designing their yaks. Regardless, this kayak was exactly what I expected, performed like I wanted, and is as represented. If I had designed it myself, I'd be extremely pleased.