He doesn't get an extra attack, so give him a single lightning claw (or proxy it, if the game is friendly). You'll have all wounds rerolled instead of only one. And digi-weapons will become free points.
I second the lord of Ultramarines - if there's Land Raider (and marines!) on the field, meltaguns will be of more use than flamers.
This guys are deadly for sure, but if their mighty AV11 dies in the firefight, they'd have to walk their way into the melee. So I'd suggest you to take one PW away or at least swap it for 2*LC - for the sake of having cheap throwaway model in the unit.
HKM on a AC/las Pred is like a TNT rigged to the nuke. If you really need it - give it to some other Rhino to split fire. And if you hope to get extra punch against LR - it won't likely to work.
If you'd take this advise and have some spare points afterwards, you may consider:
a) giving Lascannon to one of the Tac squads (to have a really great long antitank punch);
b) giving a plasmagun to one of the Tac squads (to cheer up opponent's Termies);
c) giving a Relic Blade to the Captain (pretty standard combo).
Good list, btw (everything I've suggested is just hair-splitting).
May the Emperor be with you.
