That's the point!
eng fail btwn v1 and v2 -> maintain v2
eng fail btwn v2 and v2+15 -> maintain gained speed
eng fail btwn v2+15 and higher speed -> convert excess speed to hight and maintain v2+15,
because this speed equals about vx (for JET a/c).
That's what improved climb is all about.
Big difference between PROP & JET?
PROP vx is much closer to vs than in JET aircraft.
So acceleration may make sense, i.e. if the lim fac is a far out obstcl. and your in a JET. On the other hand, acceleration (during night in IMC) in a close in obstcl. situation will screw your day.
RGDS
ADUBI