Hang on a minute. Boeing inhibited the aural warning at 100kts. Why? I'll bet they reckon that if a warning pops up after 100kts, there is a higher risk that you'll stuff up the reject than getting airborne and dealing with the possible windshear. Also remember that from line-up until 100kt, you have had ample time to actually look at the radar and spot the massive red blob that would/could produce a PWS warning and that if the sky is clear then, there's no way a windshear-potential Cb is going to create itself in the ensuing seconds it's going to take to get airborne.
Are you seriously going to reject at V1-20? -10? if the PM spots the PWS icon on the ND?