Replacing Business Connnector with SAP-XI

Hi Experts,

In our project there was a scenario in which we are sending XML data from R/3 (4.6 version) to the Target system via a middleware called BC (Bussiness Connector).

Now the R/3 system is going to be upgraded to ECC 6.0 version and as R/3 is going to be upgraded to ECC 6.0 we have to use SAP-XI inplace of BC.

Can anyone please let me know why cant we use BC (or) what problems will we face if we use BC for the ECC 6.0 version.

Thanks and Regards,

Pruthvi