Scisco,

One of the major mechanical benefits of being a rogue is the inexpensive training point cost of the hiding and ambushing skills (and subsequent mechanical benefits that come from ambushing/attacking from hiding) With the current game mechanics, there are only a few reasons where a rogue might NOT train to full plate (ability to field cast spells, using points for other skills, etc). The mechanical benefits of wearing full plate are still overwhelmingly powerful - you will be more difficult to hit, will take much less damage when you are hit, and will suffer lower critical injuries. This comes at the expense of a lot of training points, but not much else.

If you aren't interested in hiding or ambushing during combat (or using a bow), I might recommend rolling up a warrior - their training point costs and benefits of that class are designed for the combat style of out-in-the-open slash and shield.

With a game this rich and complex, I'm obviously simplifying some things, but I wanted to pass along the basics.