Well, I'm not so sure about the size being an issue. Currently, the H&K VP9 is a very popular pistol and one which major manufacturers are making AIWB holsters for. The slide length is longer than ours with the XD-9 and the magazine capacity is also greater. So, IMO, it's the fact the the XD-9 is an older model handgun that is the limiting characteristic here. You and I might say it's a classic. However, in the ever changing landscape, it's perhaps been overshadowed by the avalanche of newer pistols in the past decade or so. In fact, some of the trainers I've recently watched have commented that a smaller pistol is less comfortable carrying AIWB! Sounds counter-intuitive to me, but, hey, I have yet to carry that way. Thus, my inquiries about quality holsters. And, the comment on the VP9 was just an example. I've checked out several good holster makers and they are making AIWB holsters for plenty of midsize to full-size pistols. Just not the XD-9. If I hadn't had my slide cerakoted and an XS Big Dot front sight put on, maybe I'd just give up on it and buy a newer pistol. But, I like this pistol, shoot it well, and I've had it a long time. I have three quality holsters for it, but none in AIWB.