This is only an opinion, but:

I would rather keep to a single syntax for de-referencing when possible. As with most things in perl, there is more than one way to do it, and different ways have different strengths. In some cases using the @$arrayref; %$hashref; $$scalarref may be better, and in others $arrayref->[0]; $hashref->{key}; may be better. That having been said... @$data[$i]->{key} uses two different syntax's for de-referecing, in the same statement. I'd say that $data->[$i]{key} is much clearer.