Prevent UnityVS continually re-writing VS project files (e.g. "target framework")

Decided to bite the bullet and write a ProjectFileGeneration util. Works. Here it is for anyone else who runs into the same problem:

 using System;
 using System.IO;
 using System.Linq;
 using System.Text;
 using System.Xml.Linq;
 
 using UnityEngine;
 using UnityEditor;
 
 using SyntaxTree.VisualStudio.Unity.Bridge;
 
 namespace Assets.UGS.UnityUtils {
 
     /// <summary>
     /// Modify Editor project file generation to use <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>.
     /// Based on http://unityvs.com/documentation/api/project-file-generation/ 
     /// </summary>
     [InitializeOnLoad]
     class UnityVSProjectFileHook {
 
         // necessary for XLinq to save the xml project file in utf8
         class Utf8StringWriter : StringWriter {
             public override Encoding Encoding {
                 get { return Encoding.UTF8; }
             }
         }
 
         static UnityVSProjectFileHook() {
             ProjectFilesGenerator.ProjectFileGeneration += (string name, string content) => {
                 Debug.Log(string.Format("{0} starting on \"{1}\"", typeof(UnityVSProjectFileHook).Name, name));
                 var document = XDocument.Parse(content);                    
                 var assemblyName = document.Descendants(XName.Get(ASSEMBLY_NAME, SCHEMA)).FirstOrDefault();
                 if (null != assemblyName && assemblyName.Value.Contains(ASSEMBLY_CSHARP_EDITOR)) {
                     var target = document.Descendants(XName.Get(TARGET_FRAMEWORK_VERSION, SCHEMA)).FirstOrDefault();
                     if (null != target && target.Value.Contains(FRAMEWORK_EXPECTED)) {
                         target.SetValue(FRAMEWORK_DESIRED);
                         Debug.Log(string.Format("{0} set \"{1}\"'s {2} to \"{3}\"", typeof (UnityVSProjectFileHook).Name, name, TARGET_FRAMEWORK_VERSION, FRAMEWORK_DESIRED));
                     }
                     var targetProfile = document.Descendants(XName.Get(TARGET_FRAMEWORK_PROFILE, SCHEMA)).FirstOrDefault();
                     if (null != targetProfile && targetProfile.Value.Contains(PROFILE_EXPECTED)) {
                         targetProfile.SetValue(PROFILE_DESIRED);
                         Debug.Log(string.Format("{0} set \"{1}\"'s {2} to \"{3}\"", typeof(UnityVSProjectFileHook).Name, name, TARGET_FRAMEWORK_PROFILE, PROFILE_DESIRED));
                     }
                 }
                 var str = new Utf8StringWriter();
                 document.Save(str);
 
                 return str.ToString();
             };
         }
 
         private const string SCHEMA = @"http://schemas.microsoft.com/developer/msbuild/2003";
         private const string ASSEMBLY_NAME = "AssemblyName";
         private const string ASSEMBLY_CSHARP_EDITOR = "Assembly-CSharp-Editor";
         private const string TARGET_FRAMEWORK_VERSION = "TargetFrameworkVersion";
         private const string TARGET_FRAMEWORK_PROFILE = "TargetFrameworkProfile";
         private const string FRAMEWORK_EXPECTED = "v3.5";
         private const string FRAMEWORK_DESIRED = "v4.0";
         private const string PROFILE_EXPECTED = "Unity Full v3.5";
         private const string PROFILE_DESIRED = "";
     }
 
 }