The one redeeming feature of the FB is the DECT base station features, allows me to use cheap DECT cordless phones.
All I use my FB7390 for is VOIP, where it excels at
I can't fault it at all in that regard, and would get another do to just the same thing, pricing has come down of late on these.
Never used the Wifi as R7000 excels at that
And as of very lately the ERL-3 excels at routing, this before was done by the R7000 which is also OK at it but not great.
Never really got inspired to use the FB as a router.
I didn't use the xDSL feature either as the DV130 did a better job at that in both aDSL and vDSL
The 7390 is an OK device that does a bit of everything, excepting VOIP none really well
On a budget its a device that will get you started with once device and then leave you wanting more :)