I personally don't really like that construct, but I have seen it used. I really think that it is just a matter of preference. Using the return eval construct, makes you function behave more like a built-in function, returning a status and setting an error variable($@) if needed. This can be done many other ways as I'm sure you are aware(TIMTOWTDI).

I haven't ran Benchmark, so I'm not sure, but this seems like it would be slower than just checking the return status, setting an error variable, then returning.