Actually, the same one you have! The Sewellia are calling me; I have never even seen a live one, and don't order fish online, so it's been pretty easy to resist so far.
I also have several Panda Garras in one of my tanks that would be well-suited to this type of set-up.
I always tell myself that my next tank will be a biotope...but then time passes and stock changes and I corrupt that idea. I put in fish from one area...and then add fish with similar requirement but from a different area of the same continent...and end up with more fish from halfway around the world in there.
My 360 started with a couple species of Gymnogeophagus from Uruguay and environs...quickly got an infusion of Goodeids from Central America...and now also has a school of Odessa Barbs and the Pandas. I've even been thinking of adding some Danios just to have more surface activity.
The closest I have come to actual biotope tanks is some native tanks I had in the past, populated with fish I collected myself locally. I have considered doing a rheophile tank with darters...but having moved to a different province almost a decade ago, my current locale is sorely lacking in darter species, at least compared to where I lived before. Also, I would want the darters in cooler water than my other fish, so couldn't add their tank into my existing system; it would need to be a stand-alone, which calls for a lot more work, more space, more...more...more...