The reason people favor using quads over triangles is because most UV mapping tools works better with triangles, and some only work with triangles.
That being said, nothing prevents anyone from working with triangles or even Ngons if you want.
In any case, Blenders UV tools aren't exactly great IMO; so in my experience using quads or triangles doesn't make a lot of difference..
Dox: this looks good; very organic. I like the multi-leveled structure. You must have spend a bit of time on this. Is that the ice Age you started working on wayyyy back?
UV mapping complex landscapes is always a pain, but it's possible. It all depends on the amount of time you are ready to spend on it.
With decals, and vertex alpha painting there are many possibilities. Look at what is done in Gira, Relto, or the Cleft, for instance. It is quite time consuming though; especially if you want to use the Gira trim decal technique.. Vertex alpha painting gives decent results though, and it is much easier to use.