The Shield is compact, reliable and is rated for +P ammunition. Mine has never malfunctioned and I have never seen one malfunction. I like the thumb safety for IWB carry. Heinie makes a set of his excellent "straight 8" tritium sights for the Shield.
You won't go wrong with a Shield. The G43 is still an unproven quantity and has no thumb safety.
I recently switched from Speer Gold Dot 124 +P short barrel loads to Federal HST 147 grain +P, which shoot to the point of aim with the Heinie sights.
