Then what would stop you from going practically pure wizard, except you get to walk around in plate?
Anyways, things may look different when the final rules are released. It's all just speculation now.
except psion, monk and assassin are not playtests but previews
No technically about it. It a complete, finished class that's not going to be published anywhere else. It's not playtest or preview.Well, technically, the assassin is a finished product, isn't it? The whole DDI exclusive deal, and such.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.