FvM is correct (surprise!). If designed properly, the current transformer acts as a current source, and thus the Vf of the diodes are meaningless. With the diodes, you'll want to make sure they have a fast recovery, but it seems like you've selected good diodes (so long as they can handle the current!).
The main source of error in a CT is from magnetizing inductance. A good model of a CT is a current source in parallel with magnetizing inductance (just the inductance of the CT by itself). The current source delivers the primary current reduced by the turns ratios. Ideally all this current flows into the burden resistor, but in reality some of it flows into the magnetizing inductance, inducing error in the measurement. As FvM implies, the magnetizing inductance can saturate, causing the errors to increase greatly. So for a decent measurement, make sure the magnetizing inductance has a large impedance relative to the burden resistance, and that it can never saturate under any circumstance. Preventing saturation means making sure no DC flows in the core, and that Br resets itself to nearly zero every cycle.