Generally a professional grade sight pusher is the most efficient method. However, some mfg. e.g. Novak, recommend their tritium vial sights should be removed only by the punch method which is counter-intuitive only to those that don't understand the principles of proper sight installation setup.
Whether using a dedicated sight pusher or punch technique, most sights are easy to swap out IF one adheres to a few principles of understanding.
If using punches:
1. Properly secured in a padded vise in order for the force of the punch tip to fully deliver its impact to the sight base.
2. Tape protect all contact surfaces, smooth vise inserts, the slide and brass punch tips.
3. Shape the end of the brass punch with a file to maximize its surface contact with the base of the sight AND still fit thru the narrowest part of the dovetail. Dawson includes a proper shaped aluminum punch with each sight. The rationale for using a softer material punch is that its working end is easily shaped with a file to exactly / closely fit the contact surface on the side of sight base.
4. Rear sight, loosen the red Nylok (not Loctitie) 1/16" set screw with a high quality tool so you don't strip the hex engagements.
5. Prior to attempting to move the sights, consider using a penetrating oil and be patient for a few minutes. Even if you do everything correctly, a brass punch may deform and not displace the sights. You may need to use a proper sized steel starter punch.
On installation, make sure you can ("interference fit") insert the sight ~20-25% into the dovetail by hand. This assures the sight / dovetail edges are in alignment so you don't snowplow drive the sight crooked into the dovetail of the slide, ruining both surfaces. Fit the sight by stoning the bottom edge of the sight a few strokes at a time until its correct, the referenced diagram illustrates the principle. Dawson recommends using a file to just break the leading edge of the sight to allow its initial interference fit insertion. The selection of sight punch material (steel, brass, aluminum, nylon etc) is also generally immaterial when removing / installing sights, because you obeyed the first principle of properly preparing the sight for installation. As a gunsmithing principle, use a punch constructed of a material hardness equal or less than the hardness of the sight construction; most sights are steel or alloy, although some like Glock's are polymer construction. I also prefer use a dab of Loctite 620 (small gap adhesive) as it seems to secure better than blue / red loctite.
Even MGW cautions that the tool is not designed to remove factory “tight” sights.
IF you choose to use a sight pusher make sure it’s a high-quality one that allows correct force application to the sight base.