The tools are completely compatible with the Broker/Enterprise Server of any version. However, back versions of the Broker tools (broker_load/broker_save) or other Enterprise Tools will not be able to deal with the resulting integrations.
For example, a Join construct is new to EI 4.5.1. This construct can be stored in any Broker/Enterprise Server but the 4.1.1 EI and broker_load/broker_save will fail due to the new construct.
EI 4.5.1 will warn you if a future version has been used on a given integration (EI 5.0, for example). Unfortunately, 4.1.1 can not do the same.
#webMethods#Integration-Server-and-ESB#webMethods-General