The convergence of optical metro networks with small data-centers at the edge is reshaping how optical nodes and networks are architected. This paper explores the architecture of the metro aggregation node and its effect on edge data-center dimensioning requirements. Through network simulation on a wide range of chain topologies and load profiles, we evaluate the extent to which direct lightpaths between aggregation nodes can be used to load balance server utilization. This enables to understand how optical layer flexibility interworks with service bandwidth and latency requirements to shape the best trade-offs between server, line system and transponder costs.