[.NET] ¿Cómo trabajar async con Enterprise Library?

EntitiesController_v1.cs

using AEL.Api.Entities;
using AEL.Api.Repositories;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Web.Http;

namespace AEL.Api.Controllers
{
    public class EntitiesController : ApiController
    {
        public List<MyEntity> Get()
        {
            var repository = new MyEntityRepository();
            return repository.GetAllEntities();
        }

        public void Put(MyEntity myEntity)
        {
            var repository = new MyEntityRepository();
            repository.Update(myEntity);
        }
    }
}

EntitiesController_v2.cs

using AEL.Api.Entities;
using AEL.Api.Repositories;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Web.Http;

namespace AEL.Api.Controllers
{
    public class EntitiesController : ApiController
    {
        public async Task<List<MyEntity>> Get()
        {
            var repository = new MyEntityRepository();
            return await repository.GetAllEntitiesAsync();
        }

        public async Task Put(MyEntity myEntity)
        {
            var repository = new MyEntityRepository();
            await repository.UpdateAsync(myEntity);
        }
    }
}

MyEntityRepository_v1.cs

using AEL.Api.Entities;
using Microsoft.Practices.EnterpriseLibrary.Data;
using System;
using System.Collections.Generic;
using System.Data.Common;
using System.Threading.Tasks;

namespace AEL.Api.Repositories
{
    public class MyEntityRepository
    {
        public List<MyEntity> GetAllEntitiesAsync()
        {
            var database = DatabaseFactory.CreateDatabase();
            var entities = new List<MyEntity>();
            
            using (var reader = database.ExecuteReader("[dbo].[myTable_sel]"))
            {
                var a = reader.GetOrdinal("Id");
                var b = reader.GetOrdinal("Names");
                var c = reader.GetOrdinal("Address");
                var d = reader.GetOrdinal("Email");
                var e = reader.GetOrdinal("Code");
                var f = reader.GetOrdinal("Lat");
                var g = reader.GetOrdinal("Lng");

                while (reader.Read())
                {
                    entities.Add(new MyEntity
                    {
                        Id = reader.GetInt32(a),
                        Names = reader.GetString(b),
                        Address = reader.GetString(c),
                        Email = reader.GetString(d),
                        Code = reader.GetString(e),
                        Lat = reader.GetDouble(f),
                        Lng = reader.GetDouble(g)
                    });
                }
            }

            return entities;
        }

        public void Update(MyEntity myEntity)
        {
            var database = DatabaseFactory.CreateDatabase();
            using(var connection = database.CreateConnection())
                database.ExecuteNonQuery("[dbo].[myTable_upd]", myEntity.Code, myEntity.Email);
        }
    }
}

MyEntityRepository_v2.cs

using AEL.Api.Entities;
using Microsoft.Practices.EnterpriseLibrary.Data;
using System;
using System.Collections.Generic;
using System.Data.Common;
using System.Threading.Tasks;

namespace AEL.Api.Repositories
{
    public class MyEntityRepository
    {
        public Task<List<MyEntity>> GetAllEntitiesAsync()
        {
            var taskCompletionSource = new TaskCompletionSource<List<MyEntity>>();
            var database = DatabaseFactory.CreateDatabase();
            database.BeginExecuteReader("[dbo].[myTable_sel]", (asyncResult) =>
            {
                try
                {
                    var entities = new List<MyEntity>();

                    var db = (Database)asyncResult.AsyncState;
                    using (var reader = db.EndExecuteReader(asyncResult))
                    {
                        var a = reader.GetOrdinal("Id");
                        var b = reader.GetOrdinal("Names");
                        var c = reader.GetOrdinal("Address");
                        var d = reader.GetOrdinal("Email");
                        var e = reader.GetOrdinal("Code");
                        var f = reader.GetOrdinal("Lat");
                        var g = reader.GetOrdinal("Lng");

                        while (reader.Read())
                        {
                            entities.Add(new MyEntity
                            {
                                Id = reader.GetInt32(a),
                                Names = reader.GetString(b),
                                Address = reader.GetString(c),
                                Email = reader.GetString(d),
                                Code = reader.GetString(e),
                                Lat = reader.GetDouble(f),
                                Lng = reader.GetDouble(g)
                            });
                        }
                    }

                    taskCompletionSource.TrySetResult(entities);
                }
                catch (Exception ex)
                {
                    taskCompletionSource.TrySetException(ex);
                }
            }, database);

            return taskCompletionSource.Task;
        }

        public Task UpdateAsync(MyEntity myEntity)
        {
            var taskCompletionSource = new TaskCompletionSource<bool>();

            var database = DatabaseFactory.CreateDatabase();
            var connection = database.CreateConnection();

            database.BeginExecuteNonQuery("[dbo].[myTable_upd]", (asyncResult) =>
            {
                try
                {
                    dynamic states = asyncResult.AsyncState;
                    var db = (Database)states.database;
                    var cn = (DbConnection)states.connection;

                    db.EndExecuteNonQuery(asyncResult);
                    cn.Close();

                    taskCompletionSource.TrySetResult(true);
                }
                catch (Exception ex)
                {
                    taskCompletionSource.TrySetException(ex);
                }
            }, new { database, connection }, myEntity.Code, myEntity.Email);

            return taskCompletionSource.Task;
        }
    }
}