There is no way to provide such an estimate, because it depends on processor speed, bus speed, drive speed, and the exact number of files and how many pieces (called "extents") they are in.
There is clearly a problem noted by some users with the Volume Rebuild tool in TechTool Pro 10.0.1. The programmers are working on this reported problem, after having reproduced it. Please send a message to
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. You will receive a reply by email on Monday, and may be asked to send in some additional information, such as an Apple System Information report. You may also be asked to test a beta build of the program intended to address reported problems with the Volume Rebuild tool. Thanks for your cooperation.