I prefer that the Bajorans stay in plan DS.
Oneiros has all ready said that diplomacy with the Syndraxians is out of our hands with their opinion so low, and what makes you think the SBZ will be there forever if we form it? Once things are hopefully peacefully resolved with them, we can just abolish it, but until then having it means that events with them happen there instead of within our space.
Firstly, I missed the bit about all diplomacy being out of our hands. Thank you for telling me.
Second, I don't think it will necessarily be there forever. That is an awfully long time, after all. If I were to put it into words, what I suppose I do feel is that it will be there longer than it's really worth. Let's say we make the Border Zone. This action, in and of itself, will not stop the attacks. You say it will move the encounters out of "our space", but functionally, what does that mean? There won't be civilians nearby so much, perhaps - but from what I can recall the only time the Sydraxians got past the forces we already have in place was when we deliberately pulled those forces away earlier. Beyond that I cannot think of a single instance of the Sydraxians getting past to do much of anything, really. So the Border Zone, as I see it, removes a risk that has never been realized, in exchange costs us more ships, bases, and so forth to maintain, and in the end does nothing at all to resolve or reduce the number of attacks.
Another factor I only fully realized after that post is this: the Sydraxians seem too small to require a Border Zone.
Allow me to elaborate. Let's take a look at who we have Border Zones with at current:
Romulan Star Empire. Fought a very large-scale war in the backstory, warships are a very credible threat to our own, relations have only experienced thawing very recently and both sides are very happy to keep each other at arm's length for the time being.
Cardassian Union. Are in a state of constant smirkishes against our own forces, or at least prior to the Kadak-Tor sitiuation they were and I see no reason for that to have changed. Warships are on a general rough parity with our own vessels and we've recently discovered that their fleet in total is currently larger and more powerful than our own, are at a minimum heavily suspected for souring relationships between the Federation and various other species in between them and us multiple times in the past, diplomatic relationships only opened
incredibly recently due to an ongoing crisis.
And then we have the proposed Border Zone. Sydraxian Hierarchy. Looking at the most recent map I can find they appear to have control of a grand total of two planets, and even assuming the map to be incomplete they're smaller than the Federation by several factors. Have been defeated by our standard garrison forces multiple times in the past. Less a threat, more a nuisance.
Comparing the two we already have in place to the proposed one, the Sydraxian Border Zone looks an awful lot like overkill. At least, that's how it seems to me.