Is this good for 1000's of elements?

[XeonG]

Would it work well with adding new data elements in and refreshing where each element might have a different height kind of using example 2, but inserting more elements into it.

[aillieo]

Thanks for your interest.
That depends on how you get your size of one element (which is defined by itemSizeFunc), and this function will be called 1000 times if you have 1000 various sized elements when refreshing. And I don't think it would be a bottleneck if you have the sizes of your old elements cached when inserting new ones.