Hi Wim,
Here they grow beautifully in full sun, so I would suggest the same with you. The more shade they get, the leggier they will be, and flowering may be reduced. They do great in our slightly acid soil (pH 6), but that is not to say they require it. We are close to the edge of its hardiness range here. The first year in the ground they set loads of flower buds but they all abort in late winter, the second year a few do, after that they are fine. If the winter is very cold they can lose some wood also. The problem is desiccation - until the roots get below the freeze line, they can't take up water when the ground is frozen and the flower buds can't expand when they need to. I have 5 plants of 3different clones of E. chrysantha and also 3 plants of E. papyrifera Akebana - the latter is smaller and orange flowered, and seems slightly less hardy, although I now have 3 established. The first one lost all top growth the first winter and I thought it was done for, but it broke from the base the following summer.
Best,
J.