Yes and no. AC has always had better acceleration properties than DC. When the 378s were extended to 5 cars, a software update was not done for the traction packs at the time (no idea why). After upgrading they are pretty damned good!
The issue is the Watford DC Line. Due to the power supply problems there, none of the dual voltage /2 units have been upgraded as any of them could be working it. Which means when a dual voltage unit is used on the East London Line they run incredibly slow and sluggish.
There are 12 200kW (268hp) traction motors on a 5-car 378, with a total power output of 2400kW, however it's not always used to the max when pulling away in 'notch 4'. The amount of energy applied to each powered bogie, or in fact how much braking force is required, is dependent on the passenger loading of that particular carriage.
If you're traveling on the East London Line, and your train is on time, it is highly unlikely you will experience any feeling of amazing acceleration. The same applies to running on restrictive aspects. We won't be using full acceleration. South of New Cross Gate is more likely where you will feel it. You can get up to 60mph halfway between many of those stations with ease, but it's just not done. In the tunnel sections, most drivers won't even touch 'notch 4', due to the gradients and many linespeed changes, we just don't need to take it all the way up quickly.
To give you an idea on how fast it can accelerate, you can get up to 30mph halfway between Rotherhithe and Canada Water (southbound), with an uphill gradient and fully loaded. That is the same speed that northbound trains will be doing at New Cross Gate before going over the flyover.
