What is the impact of expert opinion on a trial judge's gatekeeping role?

I have to some extent taken into consideration this aspect of the judge’s gatekeeping role under the just completed “benefits” analysis, e.g. in denying admission of proposed evidence of a purported 90-95% confidence level in the propagation maps and in limiting any qualitative opinions to hypothetically put questions. But, the concerns about the risks associated with admitting expert opinion are broad: The "cost" side of the ledger addresses the various risks inherent in the admissibility of expert opinion evidence, described succinctly by Binnie J. in J.-L.J. at para. 47 as "consumption of time, prejudice and confusion". Clearly, the most important risk is the danger that a jury will be unable to make an effective and critical assessment of the evidence. The complexity of the material underlying the opinion, the expert's impressive credentials, the impenetrable jargon in which the opinion is wrapped and the cross-examiner's inability to expose the opinion's shortcomings may prevent an effective evaluation of the evidence by the jury. There is a risk that a jury faced with a well presented firm opinion may abdicate its fact-finding role on the understandable assumption that a person labelled as an expert by the trial judge knows more about his or her area of expertise than do the individual members of the jury: J.-L.J. at para. 25. In addition to the risk that the jury will yield its fact finding function, expert opinion evidence can also compromise the trial process by unduly protracting and complicating proceedings. Unnecessary and excessive resort to expert evidence can also give a distinct advantage to the party with the resources to hire the most and best experts - often the Crown in a criminal proceeding. All of the risks described above will not inevitably arise in every case where expert evidence is offered. Nor will the risks have the same force in every case. … As when measuring the benefits flowing from the admission of expert evidence, the trial judge as "gatekeeper" must go beyond truisms about the risks inherent in expert evidence and come to grips with those risks as they apply to the particular circumstances of the individual case. (R v. Abbey, supra at paras 90-92)