The pocket sheaths look nice, but I've never really been bothered by the knife shifting position in my pockets. And as a large man who wears large pants, sometimes the knife goes from vertical to horizontal when in my pocket--but I'm use to that as virtually every pocket knife I've ever carried has done that. The only thing I would find the other pocket sheaths good for is being able to pull the knife straight out, but with my spare tire and extra meat under the denim I'm not gonna risk slicing up some bacon if you know what I mean.
Personally I think the stock Izula sheath is one of the best sheath designs to come by default with a knife. It has very good retention that lasts reasonably long ( though it will wear out over time ) and it has such a huge, versatile array of carrying options available. There's so many ways to carry with the stock sheath...
-The lanyard hole provides for easy neck carry, an obvious
-The rail and screw holes allow for a myriad of other attachments: molle adapters, tek-loks, I think i've even heard of people using the Spydie clip
-Lashing with paracord and cord lock also provides a lot of flexibility in how to attach it to gear without aftermarket attachment accessories
I personally carry mine on my belt with a Boker Mini-Teklok, horizontally configured. I use to use paracord but I like to be able to quickly unclip the bottom of the teklok and take it off my belt. I also used a molle adapter for a long time, which was nice because because I could set it at virtually any angle I wanted, not just vertical or horizontal. And of course there's the ESEE pocket clip, which is a nice rigid steel clip that attaches to the back and can be put on the belt or slipped over the pocket.
Anyway, I wouldn't knock the Izula sheath. The retention will wear out over time though, so plan on replacing it in the future. About $20 shipping and everything, so buying one of the pocket sheaths off knives ship free for $25 might not be a bad investment.
Also, the great thing about the Izulas is the amount of aftermarket scales and everything available, and since it's so popular a lot of custom makers out there already are making semi-custom products, and have templates for them to make totally custom sheaths/scales as well.
As for interesting carry methods... With the tek-lok, when I'm around the house I like to clip it to the collar of my shirt. Hangs out the outside and stays in one place, so it's kind of like a neck knife but even better in my opinion. I don't really like to go out in public with it like this ( have had a few shop owners and people comment on the knife hanging off my shirt when I've forgotten ) so I take it off and clip it on my belt or slip it in my pocket when I go out if I'm wearing more casual pants that day.