First of all,let me thank you veterans for making some interesting points there.
Now @ Goyder
I was thinking of not taking sentinels,I am aware of the fact that they have AV10,and that they are paper like,but here is an interesting fact...
Sentinels are walkers,they could have range 48"- well beyond h.bolter range.
Packing an Autocannon,firing two shots per turn(math says they hit once).Providing I deploy them behind cover,completely out of LOS,they will get to fire.When they do,3 of them will land 3 hit on the average vs a side AV of a tank(most of the time being 11),this gives me a penetrating hit with a bit of luck,or glancing if I´m not that lucky...the tank doesn´t fir back.
Remember that they do stand beyond 36"...
Also taking 3 of them in 3 different fast attack choices buy them time,since the opposition doesn´t have 3 units to waste firing at sentinels...
So,it takes 3 units to destroy 3 sentinels...
Plus another thing comes to mind...
Let´s say I want to capitalize on that LRBT AV14,and I hide each sentinel behind one LRBT...whatever comes out is a win-win situation.LRBT is hiding the sentinel,while the sentinel is hiding the tanks rear armour...
3 Sentinels equal one LRBT...pointwise perhaps.
The list posted actually excludes the sentinels from the 1500 pts limit...the are an Option...
They do create a target rich situation for the opposition...
the unit count with them is :
Exterminator
Vanquisher
LRBT
LRBT
LRBT
Demolisher
Demolisher
Sentinel
Sentinel
Sentinel
10 models,3 of them paper tho-but my first army are DE,I´m used to not having armour(AV 10 is an excuse for armour),and I do know how to use vehicles that lack resilience.
Another intersting point is that I could play sentinels as "infantry"...OK not really infantry.If they advance (or hide) behind a LRBT,they could actually tie up units that are trying to charge my tanks.In this case,a perhaps even flamers are a good option.I don´t think sentinels are good in cc,but if you shoot the mentioned squad first(with an exterminator),and the sentinel(s),they will kill some members of the unit,and sentinels could finish the job....perhaps
One of the major reasons why I´m buying them is I´ll get them cheap,really cheap