There is no difference between interlaced and non-interlaced regarding quality from the Indivision's point of view. In non-interlaced simply every row is displayed twice, in interlace mode one picture is stored and when the second picture is transmitted, the lines from the first picture are put in between the lines of the second picture, just like it should be.
However, the overall quality of the Indivision is worse than a direct connection using MultiScan screen mode.
Bye,
Thomas