Don't think I qualify to answer this question, as experience is ever
so subjective.

Here are my thoughts going through my mind:

1. Astrigency tends to come out especially in the aftertaste, with a
feeling of dryness.

2. And yes, stronger in hot tea.

3. Especially at the later brews.

4. Some teas have longer aftertastes, with longer astringency.

5. Other feelings come out stronger in hot tea, such as savoriness
(brothiness).

6. The floral overtones tend to more dominant at lower temperature.

My two cents. I am sure the others will have vastly different opinion
and more scientific explanations.

Julian
http://www,amazing-green-tea.com