the Jewish gospels?

Time to get back on a favorite hobby horse. In sundry ways I've been asking since 2005 what difference it makes to read the gospels as Christian literature rather than as Jewish texts (for a very blunt tool looking for such questions, see here). But I have reason to raise the question again, and I don't want to miss the opportunity.

In Craig Evans's essay, "The Jewish Christian Gospel Tradition" (in Jewish Believers in Jesus: The Early Centuries [O. Skarsaune and R. Hvalvik, eds.; Peabody, MA: Hendrickson, 2007], 241–77), Evans makes the following observation:

The Jewish Gospel known to Origen may be the earliest of the Jewish Gospels (or Gospel recensions), dating perhaps to the end of the first century or, more probably, to the beginning of the second. (Evans 2007: 248)

Now for some context. First, Evans is pursuing a very difficult task, viz. "to examine the theological and practical emphases, as they may be detected, in the extant fragments of materials widely recognized as Jewish Gospels, and in closely related materials" (242). And he does so carefully and with nuance. Second, Evans spends just over three pages (242–45) discussing "Matthew: A New Testament Jewish Gospel," which he acknowledges "has been traditionally viewed as the most Jewish of the four New Testament Gospels" (242). Just over a year ago I questioned the value of the label "most Jewish", and though Evans isn't asking the same types of question I am, he is sensitive to the "profound and systemic," and even "utter," Jewishness of at least the First Gospel.

But it intrigues me that, even after the decision to apply the label "Jewish" to Matthew's gospel, Evans can still describe this fragment, which he prefers to date in the early second century, as "the earliest of the Jewish Gospels" (see above). Admittedly, Evans is referring to a very specific group of texts when he refers to "Jewish Gospels," and Matthew, I suspect by virtue of being canonical, does not fit within this group. And Evans's use of "Jewish Gospels" to refer to these specific texts—traditionally the Gospel of the Nazoraeans, the Gospel of the Ebionites, and the Gospel of the Hebrews—is entirely within the mainstream of academic parlance. Keeping in mind that I'm questioning standard practices and not Evans's specific instances of those practices, How useful is our category Jewish Gospel, and what does it reveal about us that we find this label meaningful even while recognizing the "Jewishness" of (at least) Matthew?

Is this actually a problem for biblical (and especially New Testament) research? Or am I chasing vapors?