The biggest change that Daubert (and Kumho Tire) will bring to real estate expert testimony is in the introduction and institutionalization of scientific method. There are practitioners who maintain that real estate is art, but when it comes to testimony, there better be more systematic research than has typically been found in either past endeavor, or even most current literature.
The advantage, clearly, is that some expert testimony can be challenged for its failure to meet the Daubert tests. The disadvantage is that admissible research will be more time consuming and costly than the traditional, "It is my opinion that... Therefore..."
An intriguing possibility is that "Erin Brockovich" notwithstanding, the science underlying a claim of damage may be vulnerable. In other words, even if it might be possible to show a negative value influence associated with power lines, that there is no provable public health impact from them would defend conclusively from any EMF damage claim.
More to the point, the study which would be needed to either prove or rebut a claim of market value impact would have to include a subject neighborhood and a control, dates before and after, and, whether the claimed loss was or was not forseeable. The choice of locations, dates, and evaluation of forseeability would all remain arguable, but simple assertions of damage "based on my 100 years of experience" should be excludable.