Outbound rule for Google Analytics causes 500.52 error on ColdFusion pages

Using the information here about inserting code via an outbound rule, and also encoding the Google Analytics javascript (because of the "{" character in the GA javascript), the outbound rule will correctly insert the GA code before the body code .

The process works fine for .htm pages on the IIS site with Coldfusion 9 installed, but a .cfm page (same code as htm, but with a cfm extension so ColdFusion processes it), I get a 502 error (returned by the error page processing). (Compression is turned off.)

The infrastructure is through an ARR proxy server (Windows 2008 R2 with ARR/UrlRewrite), which rewrites the request to another server (Windows 2008 R2, with ColdFusion 9.01 and URLRewrite); that second server has the page file and the outbound rule.

So a Failed Request Tracing shows the actual error as 500.52, which I believe indicates  "A rewrite error occurred during RQ_SEND_RESPONSE notification handling. An outbound rule execution occurred."

The "General Reponse Header" in the FRT shows:

Headers="Cache-Control: no-cache
Transfer-Encoding: chunked
Content-Type: text/html; charset=UTF-8
Server: Microsoft-IIS/7.5
X-Powered-By: cf9prod01"

The GA code inside the outbound rule (created via editing the web.config) is this:

<outboundRules><rule name="googleanalytics tracking script" preCondition="IsHTML" enabled="true" patternSyntax="ExactMatch"><match filterByTags="None" pattern="&lt;/body&gt;" /><action type="Rewrite" value="&lt;script type=&quot;text/javascript&quot;&gt;
   var _gaq = _gaq || [];
   _gaq.push([&#39;_setAccount&#39;, &#39;UA-35053227-1&#39;]);
   _gaq.push([&#39;_trackPageview&#39;]);
   (function() {UrlDecode:%7B}
     var ga = document.createElement(&#39;script&#39;); ga.type = &#39;text/javascript&#39;; ga.async = true;
     ga.src = (&#39;https:&#39; == document.location.protocol ? &#39;https://ssl&#39; : &#39;http://www&#39;) + &#39;.google-analytics.com/ga.js&#39;;
     var s = document.getElementsByTagName(&#39;script&#39;)[0]; s.parentNode.insertBefore(ga, s);
   })();&lt;/script&gt;&lt;/body&gt;" /></rule><preConditions><preCondition name="IsHTML"><add input="{RESPONSE_CONTENT_TYPE}" pattern="^text/html" /></preCondition></preConditions></outboundRules>

So, the question (after hopefully providing enough information): why does the HTML page work with the outbound rule, but the CFM (ColdFusion) page causes the 500.52 error?