Well if you don't have access to a separate computer, I would advise you to just delete WLM2009, install WLM2011 and try it out.
MsgPlus! v5
should be out soon for WLM2011 as well.
If you decide after a while you don't like it, you can easily downgrade back to WLM2009.
http://www.sheeptech.com/how-to-downgrade-from-wi...ive-messenger-2011