Project Finance Return Metrics

Currently having a debate with some colleagues about key project finance return metrics (mining and infrastructure).

1) Pre-tax Project / Equity IRR: What's the point of including this? I get that the impact of tax may differ depending on structure and depreciation / funding assumptions (tax shield) but the difference in Pre-Tax IRR vs Post-Tax IRR is so large it makes it kind of non-sensical compared to the impact of different follow through tax rates

2) Equity IRR: Should this be based on Equity cash outflows (initial capex funding) + FCFE OR Equity cash outflows (initial capex funding) + Distributions?

Thanks