The new Onslaught is most certainly a beast, however the Paragon with it's fortress shield (not new I know, but I hadn't fought one since the last update) is equally terrifying. Pre fortress shield I would laugh at them with my Onslaught, now I find myself hard pressed even with the Onslaught buff. The ability to unload to nearly max flux and then tank all your damage while it cools down is scary, and the AI is quite good at this, unless you're at max range and can back away when it does so. You can stop firing when it does this, and try and vent some flux, but only if it's one versus one which seldom happens.
Still experimenting with the Conquest, but it seems very good for what it's intended to be. Cap ship level guns cruising around with 150 speed is pretty scary. It was said that it isn't a cap ship killer, but that depends on the loadout. Cyclone reapers, which, in my opinion, you would be CRAZY not to have on it now that it can actually bring them to bear so easily with jets, make it a pretty powerful cap ship killer. You may not be able to go head to head with a Paragon or an Onslaught, but you can sure get behind them easy.