Not true.
Power Attack's mathematics can be applied to any power with an attack roll.
Sure Strike is not just a math adjustment, its also the choice of a power over other powers. By using sure strike, I am not using cleave or brash strike.
That's a big difference.
Over conditional usefulness in an at-will is far worse than in an feat...
because the at-will is a smaller more precious resource and has to be compared directly to another at-will which provides similar benefits preferabley.. and to me reaping strike does indeed provide similar benefits (except against minions)
For me as a DM frequency of usefulness is significant if somebody spams me with one at will because the other is only "maybe" slightly useful 1 in 5 encounters that is an argument against that at-will. I cant say it compares worth beans for
average damage dealing -
maximum possible damge or
reliability of that damage does even for his BRV fighter... versus a reaping strike done by the same fighter presented by DS see below....
An Example ..
ok lets say he fights an elite skeleton captain ac 20 that is a higher armor class on a level 3 enemy and pretty good deal better than the 18 quoted earlier.
Since he is fighting somebody higher level the odds of dwarf fighter having his brv hitpoints shrunk considerably since BRV has been nerfed but lets look with and without it
His chance to hit with a +5 attack he has to roll a 15 or better to hit that means 30 percent or 40 percent with sure strike.
the reaping strike does 2d6+2+3 damage on a hit and 3 on a miss...
3.6 + 2.1 or 5.7 damage average
and lets give 2d6+2 damage on a hit with a sure strike... well that is
3.6 + 0 or 3.6 damage.... oops.. bad sign there... its still outclassed
next round he does get his BRV damage boost... the crazy axemen gets
the damage becomes 4.4 ... doesnt compare vary well to reaping strike no not at all and that is an adversary with 20 AC.... more than a little better than the 18 quoted lets pick a higher yet adversary say
hmm his damages he quoted were 15 and 12 I have 14(12) and 11(9) I must have missed a point ( did he have a weapon focus feat I wasnt aware of?... the BRV is far from garanteed these days.
Lets pick a level 5 hobgoblin war chief shall we awesome 22 AC ....
wow to hit a 22 his poor dice will have to really dig deap a roll of 17 hits right that is 20 percent now the sure strike surely will shine better than a reaping strike.
reaping strike is now averaging 4.8 damage...sans brv bonus damage
but lets see... .3 x 9 is 2.7 and even 11 is 3.3 if
If your DM likes a lot of minions(they rock gotta love em) well that also provides very definite circumstances for using sure strike(cleave can lower its hand yes I know you can knock out two at one blow).