So will this take more than 40 hours to complete?
First, it is an Advisory Circular, so even if the proposed changes go into effect, they are not a rule. It specifically states:
"The contents of this document do not have the force and effect of law and are not meant to bind the public in any way. This document is intended only to provide clarity to the public regarding existing requirements under the law or agency policies."
Second, it appears that they are adding the option of using the Task-Based approach that is contained in the EAA Flight Test Manual:
"This AC also provides criteria for the use of an optional, operationally centric or task-based experimental aircraft flight-test plan. This task-based option provides at least the same level of safety and reliability that the existing hourly minimum 25 or 40 hour flight-test provides, but with the advantages of having operational completion criteria, a plan to record data for the creation of an AFM, and a flight-test report documenting the flight testing results."
"This AC creates the ability for builders to utilize a comprehensive, individualized task-based flight-test plan to meet the objectives of the flight-test, but according to certain completion criteria and possibly less than the typical 25 or 40 hours, depending on the complexity of the aircraft."
My read of that is you can use the task-based approach instead of the 25 or 40 hour time limit, even if it results in flying less total hours.
I will also add that for flight testing my plane I used a task-based approach that is very similar to the EAA Flight Test Manual, and I ended up finishing at 40.1 hours. So I would not think of using this approach as some way to get through Phase I faster.