GWT Activities - performance implications of using SimplePanel vs DeckPanel (card panel)

Question

In most of the Activities and Places examples I've seen, people use a SimplePanel as the display for an ActivityManager.

I was wondering if there's a benefit to using a DeckPanel/DeckLayoutPanel instead of SimplePanel. It's fairly trivial to create a wrapper around a Deck panel that implements AcceptsOnWidget.

I haven't seen this topic discussed anywhere. Prior to MVP+Activities being commonly used in GWT, people generally used Tab panels (which internally uses deck type panels) and Deck panels to control switching between panels within a given view.

The difference between the two is SimplePanel.setWidget(..) will remove the previous child from the DOM and append the new widget whereas a deck type panel will use CSS to control visibility of the current panel (i.e. "display: none" to hide inactive panels).

1. If using a deck panel, it generally means you will have much more Elements in the DOM. I would imagine this uses more memory and makes the application "sluggish", even if those nodes are not visible ("display: none"). Is this true?

2. If this is true, why did Google use a deck panel style impl for TabPanel/TabLayoutPanel instead of internally using a SimplePanel?

3. Is one approach more favorable over the other?