What I am finding on PubMed is only 14 papers on this subject of green tea and chelation of iron. They discuss neurodegenerative diseases and that the active flavinoids in green tea cross the blood brain barrier and help remove iron from the brain, which is thought to be a cause of PD and Alzheimer's.

If you use the keyword "green tea chelation" you'll see those papers. None more recent than 2010...so not much action going on with this topic.

Curcumin has quite a bit of evidence as a protector of endothelial damage of blood vessels, and all sorts of other antioxidant benefits.

I think in moderation, both are probably okay for most people.
I am using green tea to block bradykinin receptors, myself.
I only have one large mug a day. I don't drink coffee.
All of the polyphenolic compounds are mentioned as bradykinin blockers. (bradykinin is a biogenic amine involved in angioedema)

We've used grapeseed extract for years in this house. I find it helpful during allergy season.

Much of the research involves in vitro and animals. So it is difficult to be precise about these products in great detail. There is therefore alot of speculation, and not much in the way of warnings.