I think the standard assualt battlewagon loadout is about the same;
RPJ, boarding planks and riggers all have their place.
I'd say the deff-rolla get
better now that we can move 18" 1st turn to get us closer for a ram 2nd turn, plus skimmers
can't do that annoying "Aha! I dodge you on a 3+ negating all damage and stopping you in your tracks for some reason!"
They get a 5+ save if they moved but that probably won't save a raider when I hit it with 6 str10 hits!
I think what has changed is the variety of loadouts, you don't have to just have a battlewagon for taking boyz to the fight, you
can do good dakka loudouts too! Huzzah! Now that you can fire ordnance weapons and still fire all other weapons on vehicles
you could even max out all your guns and take a killkannon as well to make a soopa dakka wagon...still not a great choice
but at least it's possible.