But I didn't know about that Assembly cut and want to see it.
If you can, watch the Blu-ray version. They did the original Assembly Cut back in 2003 for the Quadrilogy DVD release, but had to use production audio for a lot of the new footage (a half-hour's worth). When the set was re-issued in 2010 on Blu-ray, Fox paid to have the actors come in and do ADR recordings of their lines, so the sound quality is perfect.