[teye]

Dude, need is a pretty strong word. Excellent caching plugins exist, and I'd venture that most WP blogs don't need them (or stand to gain much from Postgres).

"Of course none of the old plugins would work. But is that really a problem?"

WP has an incredible plugin & theme ecosystem. Whether or not you'd like to leave it behind, you can't just dismiss it like that.

Sounds like what you want is quite different from WP. Why use it?