"Because the movement is based more on Int'l style, it becomes less common in continuity Foxtrot to mix the rhythms up. And that's why Silver & above Foxtrot tends to drop the extra "slow" count, using mostly a repetitive SQQ rhythm."

There is plenty of rhythmic variation in the English foxtrot, however it is a variation applied after mastery of the swing body movement, a characteristic almost entirely lacking in the bronze american foxtrot. Bronze american foxtrot can use free (nearly arbitrary) timing variations almost as a rhythm (ie latin) dance would, wheras the swing forms must use timing variation that takes the entire sequence of body movement into account... or else look ungainly.

Yes the SSQQ patterns are mostly relegated to the american bronze with the silver and up version having a lot in common with the international foxtrot.

However the SSQQ patterns are not entirely devoid of connection to the other form - they are an expansion on a basic idea that has been used by British teachers to explain basic movement technique, and they are not dissimilar from the action in a three step, where the man has a flat heel lead walk (step seven of reverse/feather finish) followed by a gently rising one in the three step itself.