What are your thoughts on decafinated green tea? still beneficial? many thanks.

Very beneficial: Green tea has many health benefits and those benefits are not related to the caffeine but to polyphenols like egcg. Removing caffeine does not reduce these benefits and allows you to drink more green tea without the adverse effects of too much caffeine. See http://umm.Edu/health/medical/altmed/herb/green-tea for a good review of the many benefits of green tea.