So far, I have had plenty of similar snippets:
To prevent additional task creation we can do the following:
According to this article it is faster.
Another thing - the exception handling in both cases is different - here is a nice post about it.
So it is worth to get rid of async/await everywhere? Yes, but you should keep in mind some consequences:
In the first case - myDisposable is disposed as soon as the task is created - but no necessarily completed.
In the second snippet - myDisposable is disposed after stuff in DoSomeTask() is completed.