Na "zagranicznym" też się tym zajmują:
Just exchanging potential energy for kinetic energy, doesn't make a difference, as without losses. You have to re-gain the potential energy later anyhow, to achieve ISS orbit. Traditionally European launchers have relative low-thrust main stages, so loss of height during a quite long burn time is unavoidable. Compared with Atlas, Delta and Falcon, which have about 250 s of burn time compared to 540s for Ariane.