yield on www download or check www.isDone (in an update)?

Questions & Answers
1

Is there any significant difference in checking the www.isDone (in an Update function) before accessing an asset (or texture) and creating a coroutine that yields on the www?

Example 1: YieldTest would be created by a StartCoroutine.

IEnumerator YieldTest(string url)
{
    WWW www = new WWW(url);
    yield return www;

    // use www class
}

Example 2: UpdateTest would be called from a MonoBehaviour Update method. 

private WWW myWWW = null;

void UpdateTest()
{
    if(!myWWW.isDone)
    {
        return;
    }

    // use www class
}
2

If you yield in a coroutine, then you're only checking while the download is happening. If you check in Update, you're always checking every single frame whether the download is happening or not, which seems kind of wasteful (even if the actual CPU usage is probably negligible), plus the code is more complex.