I have grown Japanese acers for years, and full sun can be deadly if the acer is in the wrong spot, even when there is no wind. The critical time is early May, when the young leaves are starting to open on a frosty morning. Morning sun can wipe out all the leaves, and if the acer is young it will have no energy to generate new leaves. And, even if there is no frost, if the acer is in full sun you can get scorch that disfigures the leaves for the whole summer, especially on teh more delicate variegated / golden leaved varieties.
One other thing - they preper acid soil, can grow OK on neutral soil or slightly akaline soil if it is moisture retentive (eg loamy) but if its alkaline and dry / free draining soil, I really wouldn't bother.