Hi kostalex,
What good IEMs/canalphones (non-earbuds) have you heard before and what do they do better than the YUIN OK1 in "canalphone mode"? I would hope that the "canalphone mode" is of some use...
I liked the idea of the YUIN OK1 because it'd be convenient at times to use it as a plain earbud (when isolation is not necessary) and also at times to use it as a canalphone (when some isolation is needed).
For example, when walking in public, an earbud is much more desirable to me because of less bone conduction noises and the fact that sometimes being able to hear your surroundings is a good idea.