I've used AD8220 and impressed by it's performance for brain signal recording! Now I got to know there is another IA: AD8421 that can perform even better (or is it)? At least the spec tells me so!
I like to take AD's expert and super helpful engineers help (especially Scott and Matt) to know if i am correct or not (AD8421 is better than AD8220).
However, I'm working on prototyping a design using AD8421 for brain signal recording. I just can't wait to hear what others think.