Sitecore 7.0 Upgrade (from 6.5) Sharepoint Integration Framework 1.0 Upgrade

Part of the extra work in the SC upgrade process is making sure that your modules still work after the upgrade. Since we were using SPIF as one of our major modules, it was important that this was validated and updated as well.
From our current 111115 revision, we chose to upgrade to 1.1 rev 130613. Installation was pretty straightforward we followed the SDN instructions nothing difficult there. What struck us though was the note in one of the upgrade path; it says, upon first access, any existing integration folder will be recreated.
Whoa! This did not sound too refreshing to us as we already have thousands of references to these integration items.
We had to find out a way to sync the refs once the upgrade completes, one route we took was to leverage the SC Links DB.
We used the steps below:
1) After upgrade, rebuild the Links DB, since the web DB still contains the current live refs, we can use the media IDs here as refs once the SPIF in master has refreshed.
2) We then created a one-off page with code logic to basically do a replace operation on all referrers to the integration items. Since the web still contains our current references, we can use this and point our link DB query to web instead of master. One tricky thing here is to get all Integration files regardless of the File type (pdf, xls, png etc.). You would have to create a recursive call to get to the base template, i.e. Unversioned File in our case.

    /// <summary>
    /// Recursive call to get base templates
    /// </summary>
    /// <param name="list"></param>
    /// <param name="template"></param>
    private static void SearchTemplates(ICollection<string> list, TemplateItem template)
    {
        foreach (var baseTemplateItem in template.BaseTemplates)
        {
            list.Add(baseTemplateItem.ID.ToString());
            if (baseTemplateItem.ID != TemplateIDs.StandardTemplate)
                SearchTemplates(list, baseTemplateItem);
        }
    }

    /// <summary>
    /// Check if item belongs to the target template e.g. File
    /// </summary>
    /// <param name="targetTemplateId"></param>
    /// <param name="item"></param>
    /// <returns></returns>
    private static bool BaseTargetTemplateFound(string targetTemplateId, Item item)
    {
        var list = new List<string> { item.TemplateID.ToString() };
        SearchTemplates(list, item.Template);
        return list.Contains(targetTemplateId);
    }

3) The logic is basically three steps: 1. Run a pre-process (using the web DB) that saves all the current referrers of an integration file to a flat file.

    /// <summary>
    /// Preprocessor
    /// </summary>
    private void PreProcess()
    {

        var totalItems = 0;
        var sw = new Stopwatch();
        sw.Start();

        var resultList = new StringBuilder();
        using (new SecurityDisabler())
        {
            Sitecore.Context.SetActiveSite("shell");

            var master = Database.GetDatabase("web");
            //var core = Sitecore.Data.Database.GetDatabase("core");
            var spifLib = master.GetItem("{GUID}");
            if (spifLib == null)
                throw new Exception("SPIF Media Library is MISSING - {GUID}.");
            var spifChildren =
                spifLib.Axes.GetDescendants()
                              .Where(x => BaseTargetTemplateFound("{GUID}", x))
                              .ToList();
            if (!spifChildren.Any())
                throw new Exception("SPIF media Library does not contain any document items!");
            foreach (var documentItem in spifChildren)
            {
                ItemLink[] links;
                if (!(links = GetLinkedItems(master, documentItem)).Any()) continue;
                var item1 = documentItem;
                foreach (var delimited in from link in links
                                          let item = master.GetItem(link.SourceItemID)
                                          let field = new Field(link.SourceFieldID, item)
                                          select
                                              string.Format("{0}|{1}|{2}|{3}|{4}|{5}", link.SourceItemID, item.Name,
                                                            field.Name, item1.ID, item1.Name, item1.Paths.FullPath))
                {
                    resultList.AppendFormat("{0}{1}", delimited, Environment.NewLine);
                    totalItems++;
                }
            }

            var w = new StreamWriter("C:\\temp\\results.txt");
            w.Write(resultList.ToString());
            w.Flush();
            w.Close();

        }

        sw.Stop();
        litResults.Text = "Finished ... Processing took: " + sw.Elapsed.TotalMinutes + "mins." +
                          "<br/>Total Items to modify: " + totalItems + " " + "Total Errors: " + _errorCount;

    }

       2. Run a post process that will replace the previous IDs with the new IDs (from the refreshed SPIF tree). 3. Publish modified items.