Hi Viraj,
Point taken...However reconciling 30-40 invoices on a monthly basis (assuming monthly billing cycle) from FI-CA to FI-GL will not be cumbersome evenif, the amounts are summrised. 
Anyways, if you want to have this functionality only for a certain set of Customer accounts, which I guess you already have a indicator to segregate them from the others, and if you are predicting that the volume of these type of customer accounts is going to be constant or not be increasing significantly in the distant future, then you can use event 0061.
Hope it helps...
Thanks.
Amlan