For what its worth, I really like Termies + Chaplain + 2x Dreadnoughts in a Landing Craft as an assault formation, which can take on and usually destroys most enemy BTS formations. The intention is to put the LC into B-B with enemy as well as the Termies / Dreads, preferably with other enemy units out of B-B which allows the best LC attacks.

Note the only target this cannot take on is a Warlord or other titan of 8DC or more; it cannot go into B-B, which automatically locks the contents inside the LC, whilst leaving the LC out of contact means it cannot be used to soak up hits (and its attacks will fall on any remaining shields)

Also, at 500 points the Termie formation is cheaper and more resilient than the proposed Devastators, giving the possibility of taking a SC. And the LC allows the possibility of carrying other formations instead of the termies. . . .