Beware that upgrading to the gigabit version of this product isn't a guaranteed fix. PoE + gigabit is tricky.
For one, if all parties aren't obeying the specs, you can fall down to 100 Mbit/sec there, too.
For another, I wouldn't consider the hEX PoE a gigabit router. Instead of replacing your current hEX PoE Lite, I'd leave it in place for doing PoE duties where 100 Mbit/sec connections suffice (e.g. IPcams, VoIP phones...) and add a gigabit-capable router to it
, connected via the fiber link. Now you've got PoE + gigabit in a combo that won't fall down on you.
EDIT: I made an unwarranted assumption that because this product is in the "hEX" line it had six ports like the others, the last being an SFP. Alas,
it does not.