I think this is possible as sometimes the pages just break. Looking at your example, I'm basically doing exactly the same thing as your example code so it appears that maybe this isn't due to line feeds.
However, that's gives me another problem. When I add STREAM::max_matchsize, I get the following error.
[command is not valid in current event context (HTTP_RESPONSE)] [STREAM::max_matchsize 2048]
I've found an example of the same problem on the forum.
http://devcentral.f5.com/Community/GroupDetails/tabid/1082223/asg/39/aft/21001/showtab/groupforums/Default.aspx
I've tried adding STREAM::max_matchsize in the LB_SELECTED and STREAM_MATCHED events where I get no syntax errors, but I don't think it makes much difference.
Thanks
Darren