I would be very much interested in hearing more about these Shinko's when you get em. If you have a tire depth gauge, check em new and let me know what you show on them brand new. I think both of my other Shinko's only had 8/32s new.... but never got to ride on them as they were both recalled for delamination (Shinko 747 and 757), and the 757 had the same tread pattern that they show for the set you linked to. The tire compound on the 747 vs 757 were different I believe... just looking and feeling the tires before I sent them back.
I have tried E3's on my VTX, which are the same size as the Valk tires, and I hated them. Rough ride from the git go, terrible wear and tire life. Both wore out at the same time (which never happened with other brands I have used... usually get 2 rears to 1 front).
I just replaced a rear Avon Venom that I had overlooked.... it wears very quickly when it gets down to a certain point. I had a like new Venom mounted on a spare rear wheel that I bought from a guy that triked his Valk and put that on. Front Venom looks great still. The rear worn tired had cords showing on the left side that appeared in a cross pattern (top, bottom, left and right like a cross or X).

I have a new set of Metz ME880s mounted on a spare set of wheels in standby for the next change out. I have used Metz before, on my VTX 1800, and they handle very well but wear sooner than desired. Only reason I got these is they were the tires that replaced the Shinko 757's by the Vendor.
Overall I love the Avon Venoms and hopefully the Cobras are just as good. I would recommend Cobra's.... but would still like to hear some more feedback on those Shinko's from Farther.