I'm a huge blender fan, thank you for sharing you find, I never made any such thing for ArmA2 but it's never too late to have an attempt at it.
Also blender has a addon , in the user preferences > addon panel that is meant to do terrain, it's pretty cool. I can see it working really well. Blender is easily, my favorite 3D graphic design software. Best of all it's free and can compete with software that will cost both arms and both legs lol. One other feature is Blender has it's own game engine in it, though I never messed with it and is irrelevant to ArmA 2's game engine.
Blender is perfectly designed for such task though as you can import/export height maps, or create the terrain right there in the program using the addon provided that you just need to activate in the user preferences. I can't see any reason Blender would cause difficulties to achieve anything you want to do with arma 2, it just goes about the order in which you do it. I am a n00b at terrain and everything, I admit that no problem. But I really back Blenders capabilities, because I use it daily almost to do 3D Design. Knowing what I do know, you shouldn't need a lot of power to do the task. If you can run ArmA2, for sure you can make a terrain and use the mixture of the bi tools and Blender to get the desired out come. Just for power of your computer. Blender is better then any program that cost thousands of dollars in my opinion.
Just research some more on the process of it. As I said I am a noob, I just know Blender because I use it for other reasons. Which I have been wanting to learn things for modeling game objects, worlds, weapons, you name it and ArmA 2 is a perfect
Again thanks for the share :)
Cheers, I hope you find the answer you are seeking, Its 342am , I need to go to bed, sorry if anything i have typed doesn't make sense. lol.