Thomas, my reason for asking about Leo Brenner's claim was to get a date (no doubt listed in the publication) so as to establish the separation of Sirius A and B at that time.
Regarding the 2003-2005 observation claims, the separation for Sirius at the time is in the 6"-7" range, not the 2.5" for periastron. One would also need to evaluate the observations, because if there's only one out of say twenty observers who claim success while using 80mm, it becomes an outlier, and doubtful. At best, it means exceptional eyesight.
There's also the possibility of internal reflections in the optics, a point noted by an observer in another current thread here on CN regarding Sirius. Some observers don't check for that.
Finally, we had the experience a few years ago with another double of various folk being very certain they'd seen the companion star, and describing where it was. When a new speckle measure was made (professional observer, 4-metre scope, etc) it showed that all but one of the observers claiming to have seen the companion were getting a false positive. And there was no reason to think they were making it up. The one observer who did succeed had been uncertain whether the (extremely difficult) companion star was definitely seen: but his observations accurately fitted the real position. Others had expected a wider separation, based on a measurement that turned out to be wrong. Perhaps that had an unconscious and unintended effect on their observing attempts.
With Sirius, of course, we know with good accuracy the separation and angle. With a bit of observing practice it's possible to know, given the scale at a particular magnification, and working out the angle as seen, where to look. The angle seen in the eyepiece seems to be a problem for some. Establish West - where the drift is towards. North and South can be found by using the slow motion controls or nudging the scope (Dobs, etc). The PA (position angle) is currently about 70 degrees, so a little bit northwards from directly East. Sirius B will trail in the field, following Sirius, offset slightly Northwards from the E-W line.
Clockface descriptions in isolation don't tell you the direction. With a refractor, SCT, Mak, using a diagonal which can be rotated will change the angle; your head angle can change it too. And with Newtonians the angle on the sky, Sirius, telescope, head, will affect the angle in the eyepiece. That's why establishing your directions in the eyepiece, as above, gives you what's needed.