Hello David,
CBTA is positioned in Test Option 1 (Test Management with SAP Solution Manager) and SAP TAO is positioned for Test Option 2 (Test management with HP ALM).
Now more details about CBTA:
1. CBTA does creation of modular test in SAP SolMan as SAP TAO does in HP ALM
2. CBTA is available since SolMan 7.1 SP07
3. A recent release of CBTA in SolMan 7.1 SP12 supports SAP UI5 over and above ( SAP GUI, SAP CRM, WD-ABAP, WD-JAVA, SAP GUI for HTML, BSP). Same UI technology is supported with SAP TAO 3.0 SP04 (latest).
If you are using test option 2 - test management with HP ALM, I would recommend to use SAP TAO. Also please note SAP TAO is licensed and CBTA is available with Enterprise support contract.
Regards,
Sonal Kumar