Hi.
I'm generally just an axe/hatchet forumite, but I found this thread while playing around with the search function that my new gold membership has opened up for me. I am also a competition chopper, and I am familiar with Tuatahi's axes and grinds.
The "rolled edge" is indeed what you might call a convex edge. It is the least brash of any axe edge, but is the strongest. In competition, rolled edges are on;y common where extremely hard woods are expected, such as silvertop ash in Australia. The Banana is definitely NOT an axe grind you will want in a work axe. It will allow for pretty good penetration in soft woods, but is a style very prone to wedging and is very difficult to repair, when damaged.
The Tuatahi work axes are flat grinds, with a short chisel edge - both their older style (supposedly not available right now, due to re-tooling for the product line) and the now-available Chinese-made work axe. These Chinese axes are a pretty good deal - the head is $60 or so, but shipping is pretty steep if you only want one. Be warned, they will be very large and very heavy if you are not used to competition style axes. Probably a better axe for you would be the Keech Timberman or David Foster Work Axe (basically the same axe, with different branding.) There are several outlets for these, but I think Carson Bosworth is the cheapest/fastest, right now.
Let me know if that helps, and if you have any other questions.
-Chuck
