I never had real issues with the handling of the Vanguard. Saying that, the Vanguard and the Hornet sit right in my flying comfort zone but I found the Saber and Gladius were a little twitchy for me. I can put my nose on most targets in the Vanguard fairly quickly, which is a bad place for anyone to be.
The Vanguard is due at least a little rework, to make the module system work and to bring things up to the current standards, but it should still fit in the same speed and maneuverability area it is now with lots of bang out of the nose. In the Aegis day video they called it tweaking, but since the Warden module mesh looks to be part of the hull mesh, it is definitely going to have to spend a bit of time in rework.
And in Quantum the Vanguard is very, very fast. It gets from Olisar to Hurston much faster than the Saber, the Hornet, or the Cutlass, (They take, about 1.5 times longer to make the trip) while carrying enough fuel to make the trip 4-5 times without refueling. If things don't change longer trips are going to be much nicer in the Vanguard.