Les,
If I understand what you are doing correctly the "phaser" sound you like in this case simply comes down to a short wavetable that's being looped over with a static start point and a endpoint that creeps away from it. Approaching it from that perspective might lead to larger control over the sound. That would enable -for example- polyphony. With the technique as I presented it polyphony isn't possible without changing the timbre.
Resetting Std.srand() may be a interesting approach to modulate things in unusual ways but in larger setups it's quite limited. Then again; that limitation can lead to interesting questions and posibilities that might apeal to you.
Yours,
Kas.