Hmm...
Any time you plan to split heat uses/outputs it seems best to prioritize outcomes first..
Is your stove primarily a space heater that can dry its own wood or is it a wood kiln that can warm the shop somewhat?
If its a home heater, how much storage do you want vs instant heat vs tailpipe heat?
Storage and slow release is good. The bench, the floor (hypocaust) water, cooking surfaces, whatever you could want to heat.
Though it is nice to have a little instant radiant to goose things somewhat.. The barrel..
I find it interesting that so many rocket stove enthusiasts think the barrel is nessesary. Its just a convenience for providing instant heating to a space. The rocket stove is the insulated core. That bit does the work, the rest makes good use of the product (on one side) and convenient way to feed (on the other).
So if I wanted to build a hot water heater, I would pipe directly from the top of the heat riser through the water.. After trying it various ways, I would pipe down from the top through/around the water, then out the chimney. Better to say it with a picture..
Jays kiln would probably benefit if he got rid of the barrels and piped heat in directly from the top of the heat riser. There would be a whole lot more heat available to dry wood, perhaps allowing for a bigger enclosure (bigger batches). Of course, the thing would probably be less fun to work around on snowy days.
And then theres tailpipe heat.. Which under most home heating conditions you want as low as possible. And here at the tailpipe is where we can make a whole lot of trouble (and the opposite) for ourselves.
Assuming a chimney of some sort, you will need to warm it to get use out of it.. Believe it or not it is possible to cool the chimney (strip off its heat) to almost equal to and sometimes even below the temperature of the outside air. In this state your stove will back up and possibly even reverse its flow. So dont make your bench/thermal mass runs too long, leave some heat for the chimney.. Also, condensation of water vapor in the flowpath will happen the moment conditions are right (cool enough), so either keep temps above this point throughout or provide drainage where appropriate or both.
I typically like to see steam coming from the pipe. It strikes the right compromise for me. Typically it means a little thought twards drainage there.
If you plan on drying wood (somehow) in tailpipe heat, you will need to sacrifice somewhere else.. That is, heat available for other things, storage, instant radiant, etc.
This is why chose to place my wood box inside and heat it indirectly. It still gets plenty of heat
and all the heat stays in the house.
Yeeks!! longer post than I had in mind... Hope it helps.