i would like to build on a couple comments by previous posters, that all things being equal, in distance work, technique and stamina is what really is typically making the difference.....not the hull to the extent that they are reasonably close.

think of technique as the ability to generate power and effectively and convert it into thrust and stamina is the ability to hold a particular power output over an extended time.

what you typically find in distance work/races is the gaps really start opening up as people slow down over time as they regulate what power output they can maintain without 'pooping out' before the race is over.

a couple thoughts that i would add to the discussion:

- there a actually several efficient, good looking stroke techniques. but if you want the best potential for maintaining a relatively high power output over an extended period of time you need a style that engages the legs. in order to engage the legs you need a reasonable amount of knee bend. i love the petrel and have paddled it, but at least for me/my size, i could not get the knee bend necessary for the posture that i have when i am actively engaging my legs. there is a reason that surf skis and racing kayaks leave plenty of room for the knees to bend. paddling with the core and legs trumps the arms any day. so a high deck boat (like the high deck night heron) may be a way to get more speed potential over distance than a similar boat that does not provide the leg room to engage the leg muscles.

- stamina is primarily built with distance work so you have to put in the time on a consistent basis 'in the saddle' if you will for comparable distances/time