I've never noticed this on any of my Sebenza knives, but that isn't to say it doesn't exist. I don't think "flow through" construction really gives a knife any advantage other than possibly being cleaned. As far as strength and any other attributes, I would not think they are significant to say one knife is superior to another based on having a full back spacer vs standoffs.
I also don't really make a habit of running my finger down the back side of a blade the way you describe. Having large hands, I don't think I could get enough skin in between the knife to cut myself, not something I will be trying though. One problem I have had on another manufacturer's knife is that when the blade was closed, a portion of the blade's tip would not sit in the handle the way it was supposed to. This caused about a little over 1/16" of the very tip sticking out and caused me to cut myself. I really loved that knife, but retired it when I noticed the way it was. Having several other examples of that model, and none of them had that flaw. I would send it in, but it's no longer in production and I might get the "we cannot return this to you as it is dangerous" letter in the mail with a credit voucher for a different knife.
