Unfortunately these calculations are quite complex and not very well defined, so data varies.
The system is widely used by NGOs to make people aware of the impact of their consumption behaviour. The simple “footprint calculators” are giving rapid but far from accurate results.
The strength of the system is that it appeals to the imagination of people.
The importance is that it provides different, additional, information on sustainability: the issue of efficient land-use.
Integration of ecological footprint data and LCA data is hardly possible. Note that the eco-costs of land has been defined as land-use in terms of conversion of land.