Value of a unique weapon- the psycannon

The psycannon:  What is the value of this excellent weapon?

24" range Str 7 AP 4 Rending Assault 2/Heavy 4.  Basically a midfield can-opening super tool.

My old school metal PAGK with Psycannon

 

But the ultimate question is how many points is it worth?

The humble generic Grey Knight Strike Squad pays 10 pts for one, so do Purifiers and Interceptors.  Purgation squads pay double that at 20 pts each, but can take 4 in a squad 5 or more, while GKSS and Interceptors get 1 per 5 and Purifiers 2 per 5.  Normally you want to keep troops moving so you will be getting 2 shots per turn per psycannon. 

Now terminator armored folks get the relentless USR so end up doubling the rate of fire.  But do they pay for double the price?  Normal GK termies pay 25 per at 1 per 5 and Paladins pay 20 at 2 per 5.  Averaged out that is more than double.

Grand Master Greyen

 
So lets look at HQs-
Grand Masters pay a whopping 45 points!!  But maybe that's due to the BS of 6?  Nearly guaranteeing hits, especially if you Master-craft it.
Brother Captains (BS5) pay nearly as much, 40 points.
Ordo Malleus in Terminator Armor can get one for 15 points.

In the end is a psycannon worth the points?  Yes.  Every time.  No question about it.  I may take incinerators on my interceptors (despite higher cost) but that's due to the tank shock & shunt/jump shenanigans that are really fun.  It is also really fun to get a penetrating hit on a Rhino or other soft transport's rear armor with a flame template.  I'm digressing.  Psycannon's true power is in its kill rate and wide variety of uses.  It is the true Swiss army knife weapon of the GK codex.  A special weapon that can open AV 14 while mobile and in the hands of normal troops is pure gold.   At a relative/average cost of 1 shot per 5 points of investment it pays for itself every time.

Do I wish the old rules still applied?  Sometimes.  The 18 inch range assault 3 or 36 inch heavy 3 was very useful.  What else changed?  Used to ignore invul saves (I do miss this with the incinerators too).  But it got a str bump and now rends which is a good trade.  If you were lucky you could glance AV 12 before, now you can reliably penetrate it.

Hard to do a flame job on the new ones.

New question...Why did they change the look of them?  They look better in the old metal models in my opinion.