Poll
21%
79%
If he properly harnesses his anger, then he'll become stronger. I mean, look what he did to Dooku once he got pissed off.
And look what Dooku did to Obi...
Also, GL states Anakin is both a better duelist and more powerful than Obi-Wan on Mustafar. Had the fight continued, grief-striken Anakin would still have won.