I’ll agree with Cliffy that you’ll be much better off to find two separate holsters that excel at their given task. While there are “convertible” holsters available, every example I have ever seen requires some type of sacrifice one way or the other in order to be a dual use rig. These “convertible” holsters may ”work” in both an OWB mode and IWB mode but they often won’t work as well as a rig dedicated to one mode of carry.  

Even though I’m a dyed in the wool leather guy I’ve tried a few Kydex holsters, the Blade-Tech models included. I could never manage wearing one for more than a day though, as they never proved as comfortable or workable for me as a good leather rig.

If you’re looking for excellent concealability go for the IWB. Blade-Tech does have a very good reputation and if you choose to go that route my only recommendation would be to replace the Kydex belt loops with a set made of leather. I always found that the included Kydex loops seemed to be unnecessarily bulky and, due to the way they attach to the holster body, generally unstable.