What do you mean by stable version?
You need to always check couple of points here:
1) Always check the FMG/FOS compatibility chart
2) Always verify the released note of the target FMG , as an example ,please take a look into the page 18 of FMG6.0.2 released note. It includes the list of all FGT (and other supported devices) which are supported by this FMG.
3) Also remember FMG manages FGTs based on ADOM versions, for example, FGT which is running on 6.0.2, must be managed by ADOM 6.0.
4) You may also verify the device compatibility via FMG itself . Use diagnose dvm supported-platforms list.
Let me know if you find this explanation helpful.