Fine uses, but you can do most of that for 10 points with a Thorax Hive.
It won't be as good, but it is much cheaper.
A "general rule" for Nids is to avoid upgrades, because it is almost always better to just add more figures.
Tervigon is a "edge" unit, it is just a little over priced, so adding more cost is very unlikely to pay off.
But I have until recently used a Outflanking Tervigon, with Electro bugs as a main use unit.
It puts a Haywire Template, on a
MC, that spawns it's own bubble wrap into the foes backfield.
That causes major issues for most any foe.
I have found it is pretty darn good vs Gunline foes in particular, as the Template ignores cover.
And a Haywire Template is Made for tank filled parking lots.
If you prefer the Shredding beatles do pretty well too, and are a little better vs Space Marines. But I find that Electro bugs are "good enough" for any foe.
P.S> late entry, Also the Tervigon is Synapse, so it can babysit a Mawloc. etc...that is a major extra benefit.
Likely the best play would to drop Toxic from the Hormies, and get a second Dakkafex.