FTL usage in BusinessWorks 6.x is for mainly two things:
1. bwagent - used as a transport for internal communication 2. FTL Plugin - used to send/receive messages using FTL transport
Unlike BusinessWorks 6.x (which uses FTL as transport for bwagent), BWCE compatibility with FTL comes in picture only when there is FTL Plugin in use. BWCE 2.5.2 and FTL Plugin 6.4.4 are compatible with FTL 6.x.