Derby works on J2ME/CDC/Foundation 1.0 with JSR 169 and thus should also be able to run on Foundation 1.1since Foundation 1.1 is backwards compatible.
However the additon of BigDecimal breaks an assumption made in the Foundation 1.0 implementation, see
DERBY-2224 and DERBY-2210 for details.
I think simple changes that ensure the CDC data factory is booted rather than the J2SE data factory should fix any issues with a Foundation 1.1 platform.
I think currently the J2SE data factory is being booted becase BigDecimal exists, when in reality it requires BigDecimal and JDBC 2 or higher.
This big is not intended to take advantage of new features in Foundation 1.1, that is handled by