My Boka build.

[Yummyrum]

I did the external reflux tube because I was hoping to have a play with Reverse Liquard Management ( RLM) but haven't bothered as VM is sooo much better.
The other reason was like you mentioned ,that because I had reduced the diameter,I didn't want a choke so now vapour goes up and liquard goes around the reducer. This isn't necessary and nearly all VMs just have a reducer and there is no ill effects.
The third reason I did it was because I wanted to make sure that the reflux poured into the middle of the packing and that also means I had something to look at through the window :laughing-rolling: .This has been quite educational as I can see clearly howmuch reflux there is .

Re: some Stills have a gate valve to the RC.

If you are meaning a gate valve above the VM outlet ,then these stills are dangerous as all fuck.The Idea is close the top valve and you have no reflux so its in Pot Still mode.

Close Both gate valves and you have a bomb .THESE STILL'S ARE DANGEROUS