We currently have informal evidence that suggests that these effects make task performance in a wide area environment more productive. A formal user study that determines whether the added rendering cost of the visual effects provides a measurable user performance benefit should be performed.
The exact styles and parameters that are most effective can also be determined through a suitable user study. It may be the case that some effects work best in concert with others, or with others but only within a certain range of parameters. Choosing particular values, e.g., for level of transparency, at this point is simply guesswork.
It may be possible that the system-oriented methods for addressing lag, such as dead-reckoning and decoupling, can be integrated more closely with the visual effects we describe here. If this is the case, it might be possible to provide the user with even more information about what is happening in the virtual world and why, without confusing her.