If your current biling system is sending 4010 files, that's fine as long as you have a clearinghouse that can upgrade those 4010 files to 5010 on-the-fly like RealMed can, for example.
If you are up against the wall now, as you say, then you may wish to consider interfacing your current solutions or going with another third party biller. As Wendell has stated, and as I agree, any new PM system put out by AC most likely will not be ready for prime time until sometime summer 2012. Making a PM is as hard as making an EMR. It appears many people simply aren't aware of this.
JamesNT