I think maybe Eaves said something about it being like a micro-mini-DEFIANT ... it does have the cowled nacelles, doesn't it?
That's sure what it looks like. I just don't see something so small doing much damage to a big ship unless there are a whole lot of them. And I would hate to pilot one of those things against something like a Galor-class because just one well-placed shot and you're done.
It can probably take a beating similar to an Aeroshuttle or runabout, meaning impressively tough for its size according to the Sternbach article (an Aeroshuttle lasted a few minutes on the run being shot up by a
Vor'cha), but obviously not able to hang in a firefight like a full-scale starship.
However, Eaves' sketches appear to be indicating that the mission scoutship carries full-size torpedoes in two forward tubes and one aft one. (I am not sure if they are really "launchers" or just tubes for the torpedo to exit under its own power a la runabout module-based deployment systems.) As with the fighters and runabouts, the ability to carry full-size torpedoes means scouts like this could conceivably play a useful bomber-like role in fleet actions.
I am not sure how to estimate its warp performance. On the one hand, it appears to operate independently, but didn't look too comfortable and we must remember it was Data using this, who wouldn't need quite so much in the way of comfort and space as the rest of us. So I'm not sure it's designed for longer-term missions, like a runabout can handle. On the other hand, it is cramped in terms of pilot support but overall similar in size to a runabout and probably heavier, suggesting a power-packed ship with larger engine systems and possibly fuel reserves. On a third hand, however, it has the tucked-in warp nacelles that are supposed to result in a superior defensive envelope but inferior warp performance.
My personal guess was it was a craft with high warp performance over a short range but without great efficiency, used for scouting on an individual mission basis and not a true far-ranging "scout" in the sense we might sometimes hear the term. It has a dedicated nav deflector, heavier phaser armament than a runabout, and can carry probably something like six full-scale torpedoes or probes. I would estimate something like warp factor 6 for 12 hours, but an overall endurance notably inferior to that of a runabout; generally operated by one pilot only, it's much less versatile than a runabout but in the config I envision, would definitely be useful in a mission scout kind of role.
Finally, some have speculated that the registry on it does not necessarily mean it operates independently, and we can't be sure because there was no name. However, I think it is even less likely that a scout attached to a ship would not have the ship's name prominently displayed, as seems common for attached auxiliary craft. I do suspect it operates independently and may be named by the officer in charge, as Sisko seemed to have the ability to name runabouts; since Data was in charge of the thing, it may make a sort of sense that it was only "named" with its NCC number. (Perhaps we're lucky there is no gimme equivalent of "Spot" for ship names...or is there? We may also be lucky it was not named "Pinafore.")