Vlad,
It is of course pretty darn subjective but I just tested Powerful and Powerful+ and it is my opinion that they do what you would expect.
As a matter of fact I started with Powerful+ and it startled me - kind of knocked my socks off.
Scoping the test 2.2 version if I recall correctly Powerful+ was about 120% and Powerful was about 110% for the initial 2 sec. Which is significantly different than it was in 1.4 & 2.1 where they were all lower than standard.