There are no rules here.
Conventional reading would tell you not to stack glyphs mid-word. But that's for reading. Reading a logo is not always the primary goal.
If a logo is designed to contain some visual interest, sacrificing readability can be acceptable at times. This is even more true if the divergence conveys the word more through iconography than typographic glyphs directly.
The word "example" isn't the best use case given stacking the X and A serve as more of a roadblock than a shortcut. Stacking those particular glyphs causes the reader to stop and have to "figure out" what the intention is. But I realize "example" was merely an example. :) But it's these types of road block you should try and avoid.
In many use cases this can work well though. i.e. .... Making the "oo" in "Balloon" look like two stacked balloons.
While not the optimum configuration for reading, it does a much better job of instantly conveying the logotype brand or message.
Even something as simple as....
Offers a sense of playfulness and recognizability although it breaks traditional reading conventions.
Ultimately whether or not this type of alteration is acceptable comes down to how it's implemented and how it may effect the overall recognizability of the brand. You should never feel constricted by conventional reading structure when designing a logo though. Keep them in mind, but realize it's okay to bend or break rules at times.