Created a json converter so we don't have to use DarkMagic - this is based on a new "JSON" value type that is applied to a property editor.

src/Umbraco.Core/Models/PublishedContent/PublishedPropertyType.cs

@@ -188,19 +188,7 @@ namespace Umbraco.Core.Models.PublishedContent
             if (bool.TryParse(stringSource, out b))
                 return b;
 
-            //try json - expensive
-            if (stringSource.DetectIsJson())
-            {
-                try
-                {
-                    var obj = JsonConvert.DeserializeObject(stringSource);
-                    return obj;
-                }
-                catch
-                {
-                    //swallow, continue trying other things
-                }
-            }
+            //TODO: We can change this just like we do for the JSON converter - but to maintain compatibility might mean this still has to remain here
 
             // try xml - that is expensive, performance-wise
             XElement elt;

src/Umbraco.Core/PropertyEditors/PropertyValueEditor.cs

@@ -105,6 +105,8 @@ namespace Umbraco.Core.PropertyEditors
                 case "STRING":
                     return DataTypeDatabaseType.Nvarchar;
                 case "TEXT":
+                case "JSON":
+                case "XML":
                     return DataTypeDatabaseType.Ntext;
                 case "DATETIME":
                 case "DATE":

src/Umbraco.Core/PropertyEditors/ValueConverters/IntegerValueConverter.cs

@@ -1,5 +1,4 @@
-using System;
-using Umbraco.Core.Models.PublishedContent;
+using Umbraco.Core.Models.PublishedContent;
 
 namespace Umbraco.Core.PropertyEditors.ValueConverters
 {

src/Umbraco.Core/PropertyEditors/ValueConverters/JsonValueConverter.cs

@@ -0,0 +1,49 @@
+using System;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using Umbraco.Core.Logging;
+using Umbraco.Core.Models.PublishedContent;
+
+namespace Umbraco.Core.PropertyEditors.ValueConverters
+{
+    [PropertyValueType(typeof(JToken))]
+    [PropertyValueCache(PropertyCacheValue.All, PropertyCacheLevel.Content)]
+    public class JsonValueConverter : PropertyValueConverterBase
+    {
+        /// <summary>
+        /// It is a converter for any value type that is "JSON"
+        /// </summary>
+        /// <param name="propertyType"></param>
+        /// <returns></returns>
+        public override bool IsConverter(PublishedPropertyType propertyType)
+        {
+            var propertyEditor = PropertyEditorResolver.Current.GetByAlias(propertyType.PropertyEditorAlias);
+            if (propertyEditor == null) return false;
+            return propertyEditor.ValueEditor.ValueType.InvariantEquals("json");
+        }
+
+        public override object ConvertDataToSource(PublishedPropertyType propertyType, object source, bool preview)
+        {
+            if (source == null) return null;
+            var sourceString = source.ToString();
+
+            if (sourceString.DetectIsJson())
+            {
+                try
+                {
+                    var obj = JsonConvert.DeserializeObject(sourceString);
+                    return obj;
+                }
+                catch (Exception ex)
+                {
+                    LogHelper.Error<JsonValueConverter>("Could not parse the string " + sourceString + " to a json object", ex);                    
+                }
+            }
+            
+            //it's not json, just return the string
+            return sourceString;
+        }
+
+        //TODO: Now to convert that to XPath!
+    }
+}

src/Umbraco.Core/Umbraco.Core.csproj

@@ -334,6 +334,7 @@
     <Compile Include="PropertyEditors\SupportTagsAttribute.cs" />
     <Compile Include="PropertyEditors\TagValueType.cs" />
     <Compile Include="PropertyEditors\ValueConverters\IntegerValueConverter.cs" />
+    <Compile Include="PropertyEditors\ValueConverters\JsonValueConverter.cs" />
     <Compile Include="PropertyEditors\ValueConverters\MultipleTextStringValueConverter.cs" />
     <Compile Include="PropertyEditors\ValueConverters\SimpleEditorValueConverter.cs" />
     <Compile Include="PropertyEditors\ValueConverters\TextStringValueConverter.cs" />