Roberto,
Thank you for your kind comments.
With regard to endgames, the Shield is helpful to the weak side but can be
beaten. King and Immobilzer vs. King and Shield is a forced win--either
the King and Shield get immoilized (loss by stalemate), or the King gets
immobilized and the enemy King picks off the Shield--also a loss by
stalemate.
Against all opposing forces a King and Shield which must stay next to each
other are in extreme danger of losing by triple repetiton.
The general technique for King and X (where X is a piece that would win
vs. a lone King) vs. King and Shield is to set up a positon where the
Shield is captured by X and the lone King can't recapture. More analysis
and playing experience is needed to see how frequently this
can be forced.
King, X, and Y vs. King and Shield should pretty much always be a forced
win.
Of course. 'kill the Shield' combinations will be as much a mainstay of
the middlegame as 'kill the Immobilzer' combinations are.