Personally I don't find it difficult to alternate between the two so long as you can accept they are two different operating systems so you may have to do things a little differently or a particular customisation feature may be missing.

For the general user 99% of the core functionality required is there with only major omission being an open file system, Android you can plug into most devices and access all your files, iOS is a little more locked down.

You're absolutely right, if you aren't tied into the ecosystem they are both top tier flagship devices each with similar levels of performance and the simple fact of the matter is that the apple ecosystem and more specifically iMessage is not as prevalent in Europe as it is in the US.