Nathan,
the M3 is a fairly flat bottomed kayak, with hard edges in it. I don't understand your comment.
PB Kayaker,
As someone else said, remember that you'll get OPINIONS here, so keep that in mind as you get more repsonses. Good luck with your quest for the proper creek boat. It's a tough decision for sure.
I'll throw my opinion in here and start with an observation that I think many people try narrow things down too much into only Flat/Round. There is much more to it than that (as surely lots of observant paddlers are aware)
I got into it a bit in my blog when I compared the 3 DragoRossi creek boats
totalwhitewaterfun.blogspot.com/2006/10/...nes-and-rockers.html
and I'll add a bit more here to consider the discussion, specifically on the cross section of a kayak.
Imagine that you cut a kayak in half, from side to side, right through the cockpit. You would either get a generally round shape, or generally rectangular shape. Modern freestyle boats are very close to the rectangle shape,and old-school 4meter boats are very close to a circle or oval.
When sitting still, a rectangle shape feels more stable where as a circle would feel tippy.
The circle is easier to lean up on edge, and rectangle takes a little bit more effort.
The rectangle spreads out the paddler's weight (it \"displaces\" your weight) over a larger area, so the boat floats higher in the water: when the circular boat sinks a bit deeper into the water because more displacement happens at it's center.
This leads me to illustrate how these two extemes feel to me in a kayak.
The circular/oval cross section feels like it is riding on it's center line, like balancing a bicycle.
The rectalinear boat feels like it on two railroad rails, or more accurately like a modern roller coaster, even a jet airplane making banking turns.
Of course the reality of boat design is that each boat lies somewhere in the middle, just favoring one extreme or the other.
Examples:
Jefe is a very round boat
Mafia is a flat boat with round edges
Diesel and Mamba are flat boats with hard edges
A quick thought about edges:
Very rectalinear boats have hard edges, the sharp corners of the cross section. Hard edges run a higher risk of being tripped up by rocks on a creek so many companies tuck that edge in a bit, or round it off. By rounding the edge off, there is a higher chance that the boat will skip over more of those little rocks (kind of like extra \"sideways\" rocker). But, round the edges off too much, and you've gotten rid of the edge completely and you now have a round boat.