I really doubt that they'd last you more than 6 months regardless of getting sliced up or not. How many km's can gp5k take? 5000 in the rear? Before they are completely worn down.
I didn't get a single flat the last 14000 km using Conti Ultrasport 2 and 3. I always thought they were just cheap shit and I just bought some for my old road bike when my conti gp 4k got destroyed because that's what the shop had. Now I'm really sold on them though, obviously very puncture resistant, last a long time and according to bicyclerollingresistance.com
the ultrasport 3's have about the same rolling resistance as conti gp 4k so they aren't complete dogshit in that regard either.