Lowering the ejection port? No problems. Benefit is the ejection of shells is perhaps better than leaving it standard.
Series 70? Some smiths have seen problems with the collett barrel bushing. Go solid.
Series 80? More parts to give problems if adjusted incorrectly. (and a lot of people put the adjustable trigger in a series 80 1911 and adjust incorrectly that the serie 80 firing pin plunger does not rise enough for the firing pin to clear cleanly).
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)