Firstly I agree that the curved design would cut easier and it also would have a longer surface cutting edge.
The straight edge has its advantages too, like using it on a flat surface where the full straight edge is used without having to change the height of your hand. (Hope you understand)
If you have to sharpen it and you are in a situation where you havent got or have lost your sharpener, the straight blade would be the easier knife to sharpen, or easier to get hold of a sharpener.
The other point to consider is that the first part which will probably fail is the tip. So you want maximum stregnth at the tip which looks like the curved design will give you.
I have broken tips on knives similar to the straight design shown.

I have a similar problem to you, being that I cant find any suppliers of quality knives close. I ended up buying a couple of knives from the U.S. and another from a supplier I found across the other side of the country nearly 3500 kilometers away.
Have you searched eBay? because one of the knives I bought from the U.S. over eBay I ended up ordering 3 more for friends who wanted similar knives.