This paper evaluates the impact of Lokal Kollektiv Tarifering (LKT), a capacity and volume-based grid tariff for Danish renewable energy communities (RECs), on both REC economics and distribution grid loading. Realistic REC consumption profiles are built via Monte-Carlo sampling from high-resolution Danish smart meter and electric vehicle (EV) charging datasets, combined with sized photovoltaic (PV) production, varying community size, EV adoption, and PV penetration. Yearly electricity costs under the LKT model are compared against the volumetric-only ones, to identify when and for whom LKT becomes economically favourable. Results confirm that LKT delivers a stable, predictable DSO revenue stream while rewarding flexible, coordinated communities, but it penalises RECs with high-peak consumption periods for a full year and can discourage self-sufficiency through PV. EVs emerge as the dominant driver of peak demand, making charging coordination essential once LKT is adopted. A handbook of REC-related KPIs is also provided, to characterize Danish RECs.