The only thing I hate about OPB is their print runs seem small since the manga goes out of stock at major retailers for a few weeks following release until more stock shows up.
Not sure how much farther the LN actually goes than the WN (not far from what I've heard), but sounds like it just stalls out around the time it should be getting ready to move onto the next major arc, so I'm guessing the author either got bored, or ran out of ideas about how to keep the whole thing going without having to reveal everything.
While I think this would be a semi nice read (since I've read the WN), it's probably only worth it if the series starts up again in Japan, or JNC can get it on the cheap as part of bundle.