Is the Reaver Jetbike Grav-Talon even worth it?

The good thing about it is that it forces a pinning test
The bad thing is majority of the armies have a ld of 8 and above and you are never going to pin them even if u want to maybe if your lucky, id perfer the All handy Cluster Caltrop than the grav-talon

It's not bad, if you run large squads of reavers (9) you will on average be forcing a moral check and a pinning test. The chances of LD8 failing at least one of the tests 47.8%.

At the end of the day though just like the cluster caltrop it's unnecessary points spend on a unit that is already expensive enough as is.

I believe it can be. If you look at a unit like Tau Firewarriors or Kroot, with their massive firepower, decent max squad size and meh Ld, it is a good candidate. The idea is 3 scenarios:

1. Blade Vanes eats the whole unit.
2. Blade Vanes causes enough damage to inflict a Morale Check and a Pinning Check.
3. Blade Vanes does not cause enough damage for a Morale Check, but does cause a Pinning Check.

Scenario 3 is escpecially likely when your Reaver unit has been beaten down into a less threatening size. The fun thing about Pinning Checks is also that it effects those pesky SMs and their ATSKNF.

But you may get different mileage out of it. The Cluster Caltrop is obviously more powerful, but the lost is so high you could afford Grav Talon and Heat Lance for 2 more points. So really, it is up to you.

You usually dont need what you cant rely on, and you cant rely on pinning tests.

If you do some crazy stuff and go all over this pinning with Necrotoxin Missiles, Raiders with torment launchers, harlies with Jesters etc the pure weight of pinning tests will cut throu.

Otherwise i wouldnt bother.

Or Hexrifles or Bale Blast.

But I would debate the point of it in a tournament setting. So many armies have easy Fearless built in that it is largely a nice tactic for pick up games. Effective against enemies that are numerous, dangerous and low Ld? That combination doesn't exist in many places. And even Tau can use markerlights to mitigate the problem of BS1. So skip it.

Back when there was some confussion on whether or not the GT gave additional D3 attacks, maybe. Not now. Noooooooo.

This reminds me of the Horrorfex/Terrofex debate back under the old codex. That was a straight up shooting attack, small blast, that forced a pinning test at -X leadership where (X = the number of models in the unit hit)

So, with a small blast, typically it was a -2 or -3 Ld test or get pinned. As a shooting attack that could be attached to Raiders or Squad leaders. When it first came out it was game changing. Then, as the editions rolled around and more and more armies became semi-immune to leadership tests it became less and less quality.

Please feel free to list for me the high quality infantry units you'll see in a competitive enviroment that are less than Ld 9 or are not fearless. Take your time. There aren't many - and that's why the Caltrops are sort of a 'meh' upgrade. Sure, if you have the points, as a last choice buff it's not bad.

But I would advise against building for it or (dear gawd) actually making it part of your tactics.
That didn't work so well when our entire army could be shooting pinning templates - it won't work with the rather limited options we have currently.

If memory serves Dark Angels are a Ld8 army across the board but with stubborn to counteract this... (greenwing, that is; Death and Ravenwing differ). Tau are also in the same position - one of their major Achilles' heels (the other being the combat potential of a paper bag). Dark Eldar ourselves are leadership 8 until you start paying points for sergeant upgrades, but that's less of an issue as DE caught outside a transport are generally either a) about to die or b) going to be going to ground to max cover saves anyway. I agree though, that its not really worth it - there'll almost always be something better to spend your points on in the army.