Hyperspace near a Wormhole Junction
I don't know whether or not Richard transmitted my response to this question to the newsgroup. In case he didn't, I will recap.
Any wormhole terminus exists in a fixed relationship with the star(s) with which it is associated. Any star's gravity well produces a discernible distortion, or "ripple" effect, in the lowest hyper-space bands. These ripples are not normally sufficient to make problems for a starship simply passing through the hyper-space which corresponds to the normal-space location of the star, although such ships can occasionally encounter severe grav-wave turbulence if they get too close to the star. This ripple effect grows more pronounced as the mass of the star goes up, and the curve climbs quite steeply once you get into the stellar giant classes.
A wormhole also produces a "ripple effect" in the local h-space. A wormhole's ripple is not caused by a gravity well, but rather by the "focusing lens" effect which created the wormhole in the first place, and under normal circumstances, a wormhole's ripple has no effect at all on ships passing through its vicinity in hyper-space. But there is a zone which can be thought of as a cone in hyper-space in which the ripples of the star(s) associated with a wormhole and those of the wormhole itself produce an extremely dangerous resonance. That resonance can destabilize the fields produced by hyper generators, which invariably destroys the destabilized ships. Assuming that a starship avoids outright destruction, it will find its astrogation calculations very seriously affected, which will destroy its ability to predict its reemergence into n-space with any precision. And the wear and tear on the hyper generator and propulsive systems of any starship which survives transit through the resonance zone will be extreme. All of this is a major reason why the central terminus of the Manticore Wormhole Junction is covered by forts rather than simply stationing Home Fleet out there. Placing Home Fleet (or a sizable portion of it) out at the Junction would effectively deprive it of the ability to respond quickly and as a concentrated force against anyone attacking the inner system from another bearing.
In On Basilisk Station, Honor dropped a stitch in her explanation of the Peeps' options to McKeon. Her calculations on the speed with which the Peeps could put their forces on top of the Basilisk terminus were all based on the assumption that the Peeps would use events on Medusa as their pretext to intervene and that their fleet would head for Medusa first. A direct pounce on the terminus would have been much harder for the PRH to sell to the galaxy at large as a response to an atrocity which got out of hand, and she therefore reasoned that they would probably send any fleet to Medusa first and only then out to the terminus... which would have worked fine, if their initial plan had worked properly, because they would have had plenty of time to proceed in that fashion before any reaction from Manticore could hope to arrive. However, it would have made no real difference to her options or her assessment of the situation if they had decided to come whooping straight in on the terminus through hyper. In either case, she believed that she had to stop Sirius from reaching the rendezvous, because whichever their actual plan might have been, they would still have time to implement it before Home Fleet responded.
In Echoes of Honor, on the other hand, we do see a fleet make an h-space approach to a wormhole terminus, although I rather regret the fact that I decided to cut a few words out (I had to squeeze out something like 50,000 to get the book "down" to its final size) by grossly simplifying the reasons I have one of the defensive fleets moving away from the terminus through n-space.