We present a detailed study of the gas and dark matter properties of the 5 most massive and distant, $z \sim 1$, clusters detected via the
Sunyaev-Zel'Dovich effect. These massive objects represent an ideal laboratory to test our models of structure evolution in a mass
regime driven mainly by gravity.
This work presents a new method to study these objects, where informations coming from XMM-Newton and Chandra instruments are
efficiently combined. The combination of Chandra fine spatial resolution and XMM-Newton effective area allows us to efficiently
investigate the properties of the Intra Cluster medium in the core and probe cluster outskirts. The resulting combined density profiles are
used to fully characterize the thermodynamic and physical properties of the gas. Evolution properties are investigated from comparison
with the REXCESS local galaxy cluster sample.
In the context of the joint analysis of future Chandra and XMM large programs, we discuss the current limitations of this method and
future prospects