In this paper, we evaluate the performance perceived by end-users
with very high access rates, connected to a common backhaul link
that aggregates the traffic of multiple access areas. We model,
at flow level, the way a finite population of users with
heterogeneous access rates and traffic demands shares the
capacity of this common backhaul link. We then evaluate several
practically interesting use cases, focusing particularly on the
performance of users subscribing to recent FTTH offers in which
the user access rates may be of the same order of magnitude as
the backhaul link capacity. We show that, despite such high
access rates, reasonable performance can be achieved as long as
the total offered traffic is well below the backhaul link
capacity. The obtained performance results are used to derive 
simple dimensioning guidelines for backhaul networks.