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Im going to have to disagree. On old style EB's it made sense but with modern rubber and construction its just not worth it. You will never get anywhere near the same performance as before and it is probably quite spendy. On the old EB's they would rubber weld a new edge to the boot as well as performing the patch up, but its been a very long time since we moved away from that.
From the looks of the remaining rubber you have worn them into the ground, the seam will probably go again elsewhere soon.
Im no expert though so If in your search it turns out it is worth it and they feel great again I would love to hear about it......
It's perfectly possible to replace the sole/rand of a rock boot - I remember in the late 90s it was quite common to take new boots to a place in Sheffield that had some kind of super-sticky mystery rubber. I think it might be worth asking a re-soler what they think about the damage to the upper that you are showing in the photo, though.