EF to RavenDB with almost no work. Still have to tell RavenDB that the field with the Key attribute is the Id field, but that's minor.

wip.cs

[TestFixture]
public class SimpleTests
{
	private IDocumentStore _store;


	[TestFixtureSetUp]
	public void Init()
	{
		InterceptorCore.Initialize("EF6");
		System.Data.Entity.Database.SetInitializer<NWDocDBDataContext>(null);
		_store = new DocumentStore() {Url = "http://localhost:8080/", DefaultDatabase = "Northwind"};
		_store.Initialize();
	}


	[Test]
	public void InsertOrders()
	{
		// first fetch them from the DB using EF
		var ctx = new NWDocDBDataContext();
		var alfkiOrders = ctx.Orders.Where(o=>o.Customer.CustomerId == "ALFKI").ProjectToOrderDoc().ToList();
		// store them into the doc db
		using(var session = _store.OpenSession())
		{
			foreach(var d in alfkiOrders)
			{
				session.Store(d);
			}
			session.SaveChanges();
		}
	}


	[TestFixtureTearDown]
	public void Shutdown()
	{
		_store.Dispose();
	}
}

//------------------------------------------------------------------------------
// <auto-generated>This code was generated by LLBLGen Pro v5.0.</auto-generated>
//------------------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Documents.Persistence
{
    /// <summary>Static class for (extension) methods for fetching and projecting instances of Documents.DocumentClasses.OrderDoc from / to the entity model.</summary>
    public static partial class OrderPersistence
    {
        /// <summary>Extension method which produces a projection to Documents.DocumentClasses.OrderDoc which instances are projected from the 
        /// results of the specified baseQuery, which returns Northwind.Adapter.EntityClasses.Order instances, the root entity of the derived element returned by this query.</summary>
        /// <param name="baseQuery">The base query to project the derived element instances from.</param>
        /// <returns>IQueryable to retrieve Documents.DocumentClasses.OrderDoc instances</returns>
        public static IQueryable<Documents.DocumentClasses.OrderDoc> ProjectToOrderDoc(this IQueryable<Northwind.Adapter.EntityClasses.Order> baseQuery)
        {
            return baseQuery.Select(p__0 => new Documents.DocumentClasses.OrderDoc()
            {
                CompanyName = p__0.Customer.CompanyName,
                ContactName = p__0.Customer.ContactName,
                CustomerId = p__0.Customer.CustomerId,
                OrderDate = p__0.OrderDate,
                OrderId = p__0.OrderId,
                RequiredDate = p__0.RequiredDate,
            });
        }
    }
}

//------------------------------------------------------------------------------
// <auto-generated>This code was generated by LLBLGen Pro v5.0.</auto-generated>
//------------------------------------------------------------------------------
using System;
using System.ComponentModel;
using System.Runtime.Serialization;
using System.Xml.Serialization;
using System.Collections.Specialized;
using System.Collections.Generic;

namespace Documents.DocumentClasses
{ 
    /// <summary> Document class which is derived from the entity 'Order'.</summary>
    public class OrderDoc
    {
        /// <summary>Gets or sets the CompanyName field. Derived from Entity Model Field 'Customer.CompanyName (Customer)'</summary>
        public System.String CompanyName { get; set; }
        /// <summary>Gets or sets the ContactName field. Derived from Entity Model Field 'Customer.ContactName (Customer)'</summary>
        public System.String ContactName { get; set; }
        /// <summary>Gets or sets the CustomerId field. Derived from Entity Model Field 'Customer.CustomerId (Customer)'</summary>
        public System.String CustomerId { get; set; }
        /// <summary>Gets or sets the OrderDate field. Derived from Entity Model Field 'Order.OrderDate'</summary>
        public Nullable<System.DateTime> OrderDate { get; set; }
        /// <summary>Gets or sets the OrderId field. Derived from Entity Model Field 'Order.OrderId'</summary>
        [System.ComponentModel.DataAnnotations.Key]
        public System.Int32 OrderId { get; set; }
        /// <summary>Gets or sets the RequiredDate field. Derived from Entity Model Field 'Order.RequiredDate'</summary>
        public Nullable<System.DateTime> RequiredDate { get; set; }
    }

}