I play a lot of Dracothian Guard (my entire army is themes around cavalry, pretty awesome, and good too!) and I can say this about them in the new edition. Fulminators are still good, but the loss of the breath attack requires you to take a Knight-Heraldor, since they can't shoot their way out of combat reliably now. If they get bogged down they are really bad. I think Concussors are better. They are worse against shooting lists, but with a Castellant lantern buff and Staunch Defender it doen't matter as much. They also don't require a Heraldor as they are as good on the charge as in protracted combats, and they obliterate hordes with them preventing pile-ins. 40 skeletons are scary, 40 skeletons who can't pile in are not scary. For 20 points more they are worth it. Tempestors are only good against shooting lists, otherwise they're a waste. Find the points to upgrade them to Fulminators or Concussors. Desolators are bad, you need 8 of them in a unit to be sure of them getting their attack bonuses, and such large units are very weak to debuffs. If you face any army that can give them a -1 to hit you're in trouble. Otherwise they will of course destroy whatever they touch, but making half your army a joke to one debuff is very risky.