After 13 games my spectres have taken out: One rhino.
Yea one rhino.
Penetrating is no problem I just can't roll higher than a 2 for the damage. My opponents tell me they dont fear them at all and they get ignored for the most part.
I have used them to kill termies, they've bagged more of them than vehicles (I actually deep struck them in this game I'm talking about).
First priority IMO is big scary tanks, then MCs finally regular infantry. If there's no viable targets on the field (pure green tide) I'd opt to deep strike them to give you options as the game progresses.
Don't rely on the holofield save
Exarch + cynosure is worth it IMO for such an expensive AT unit to miss the extra points to get these upgrades makes it worth while.
Nice models, just got to buy the Exarch now he's out, probably at the end of the year or when the next Imperial Armour comes out.