Sheena, you have just sent a single enquiry in Sept 2010 after more than 1 year of receiving your 2nd AoR (Aug 2009). No doubt that frequent enquries have a negative impact but enquiry after 1 year is not frequent.
Now as you are going to make an enquiry in Sept 2011 (i.e. after more than 2 years of your 2nd AoR) & processing time of 18 months has already past, I am sure there is no harm in knowing the status of your application.
Still you may abide by the advice of your consultant & you can request CAIPS for knowing the details of your application.