The 24BHP Himalayan is a great all round bike, but does lack some punch for overtaking, and motorway work. Having said that I rarely ride it on the motorway, and I only overtake when within the limits of the bike.
The full 70 or so horses of the H2 rarely get let off the leash, reason being that I value both my life and my liscence. Personally I think it a great bike to ride, plenty of grunt when needed.
The 54 or therabouts of the speedmaster have yet to be properly tried - bought it more for 2 up riding rather than solo and have only done about 10 miles on to date, these were the miles I did trying it out.
Guess if you are doing touring / lots of 2 up riding and or motorway work plenty of grunt is what you need for comfort and safety, but exactly how much probably depends on the rider.
Plenty of cars out there with huge amounts of power as well as bikes.