The one advantage I can think of for 'cross is that often a kevlar-beaded tire can be mounted/unmounted with your bare hands. If you flat during a race this might be a benefit, I dunno.
Other than that, folding tires are useful as spares on tours.
The kevlar-bedad tires I've used have had relatively soft sidewalls; when they were also kevlar-belted the belt was only under the tread, not the sidewalls. I wouldn't have given much for their resistance to sidewall damage. These were touring tires, though; presumably a 'cross tire would be more robust.
RichC
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Training: 2002 Fuji Roubaix Pro (105 triple)
Commuting/Daytripping: 2001 Airborne Carpe Diem (Ultegra/XTR, touring wheels)
Commuting/Touring: 2000 Novara Randonee (Sora/Tiagra/LX, fenders, lights)