First Time Poster, long time reader...
First: I have read all the available HH novels, Shorts, and listened to the Audio shorts, aside from the LE event releases which are hard to obtain with me living in Canada. I agree with most, if not all of the points made regarding the length of the series overall.
Second: I feel as though BL has utilized the HH series as a "coming of age" for the 40K franchise. The Vulkan escapades in particular have more import in 40K than in the known 30K mythos. Bbobs eloquently expresses so many excellent points regarding the "overfilling" of the cup of knowledge as it relates to the core of the series. Truthfully, the series could have ended after Galaxy in Flames, as we see the initial heresy occur, the events that spawned such a massive upheaval in this far future Imperium of Man. The 40k stories are of course largely based upon the "developing" lore we are privy to as a result of the sheer obesity of the HH to this point.
As you can see, so much of the HH "fluff" or "filler" which to our current knowledge impacts the overall story minimally seems to be geared solely on laying a foundation for 40k novels, which makes sense seeing as 40k was ripe with novels prior to the release of Horus Rising.
Anyway my two cents. It is becoming far to lengthy, but like many of you, I am still reading because I am invested. I want to see what happens, not all of it, but the significant events that surround the final climax when we get to Terra. That being said, there will likely be 6 or 9 novels about the siege proper, each from a different perspective, as was pointed out hilariously in the Istavaan Thread looking at BL marketing techniques and methodology.
I just shelled out for the new Ragnar Novel(la) and eagarly await its arrival. This is one of the longest series I have invested both time and money into, likely since R.A.Salavtore's examination of the drow way back when. While I am becoming wary of the time and money spent of these novels, I still enjoy the writing of almost all the BL HH team, lately the novels have just seemed to lack significance and import during the story arc of the HH.
Death to the False Emperor!!