Manchester introduced a refillable one-pound cylinder (Manchester Tank: 1# Refillable Cylinders
) a few years ago, which looks well-designed; it has a proper service valve. The Flame King design looks to me like a disposable cylinder, just upgraded in construction; that might be okay, but seems less desirable.
It is the filling arrangement which disturbs me about the Flame King "system". This is the classic home hack which involves inherently unsafe handling of the source cylinder. I'm not so concerned about Ron doing this, but most people don't have a clue what they're doing and things can go wrong. Manchester's hose connects to a proper liquid service valve, avoiding this problem. I think one reason that Manchester's system has never caught on well is that they will apparently only sell the required fill hose to qualified propane dispensers so most people can't get the fill hose - and wouldn't have a liquid source anyway - and so they don't have a good way to fill the small cylinders.
What I consider to be a significant problem with the Flame King systems is that there is no sound control of the fill amount. With little pressure driving the fill, the small cylinder will not over-fill in a reasonable time; however, if you leave it long enough there will be inadequate (or no) vapour space remaining in the small cylinder... and most people won't check, and have no good way to dump excess propane.
The Manchester refillable cylinder has a fixed liquid level "gauge" - the same sort of bleed valve connected by a dip tube to the 80% volume level in cylinder as larger cylinders. This lets the person filling the cylinder stop the fill when liquid appears, just as with a conventional cylinder.
A member of FiberglassRV converted his Trillium to use a "forklift" tank instead of the usual "barbecue" tanks. Combined with Manchester's one-pound cylinders and fill hose, this seems like an ideal configuration: metered fill of the forklift tank whenever desired, real level gauge in the forklift tank, and inexpensively filled small cylinders to use wherever needed for stoves and grills.