Higher Grouped Classes Larger

I was subbing for a 4th grade with around 25 students.  The kids switch classes for math and I had a group of 30 students.  I was not explicitly told that they were the higher group, but this is the common way of dividing kids when they switch classes.  Usually the top group gets more students, the middle group has an average number, and the low group gets fewer students. 

And now I am pondering what the effects of this are for gifted and highly gifted students.  On the one hand, the level of the whole class can be somewhat higher.  Generally, these groups use exactly the same textbooks, but sometimes their homework or side activities are a bit different.  And, if there are exceptionally able students in the class, the teacher could possibly cluster group them (though I have never seen any indication that teachers have done so).  On the other hand, the classes are larger, which means more grading, more classroom management challenges (even finding enough places for the extra students to sit), and more communication duties (parents, homeroom teachers). 

So, is it helpful?  Probably.  Is it sufficient?  Probably not, in some cases.