Hi Mark,
E grandiflorum nanum will take more hours of your sun as its very soft compared to ours in Aus. One thing I did notice that the quality of your sunlight is very soft and throughout the northern most parts, no wonder you guys dont sun burn, you would fry here. My E g nanum takes full sun in spring until midday under a deciduous tall maple and gets shade when leafs out for summer.
hope this helps