With Rx, it's very simple and clear with

subscibeOn

and

observeOn

to do all this (but coroutines are much better in other aspects... 😉 ). In coroutines things seem much more complex in this aspect, and the 'danger' you mentioned... does that also exist in rx?

All the dangers are 100% same as in Rx. The difference is that in Rx some operations under some rare circumstances sometimes run in an unexpected thread. With coroutines if you do

run(myContext) { myCode() }

, then there is 100% guarantee that your code runs in the specified context.