200A Panel w/150A Entrance Cable?
 

Is it a problem to install a 200A Circuit Breaker panel w/an existing 150A entrance cable. Someone told me that would lead to an over-fused circuit, but thinking it through, the greater capacity "down stream" shouldn't be a problem if there is less current coming in.

Not a problem is you use a 150 amp breaker in the 200 amp panel. The cable will not limit the current. Curent will flow until the cable melts. The breaker protects the cable.

Are you planing to update your panel?
What Brand are you going to use?