I posted this on another thread the other day:
I originally had the Zagg InvisibleShield and recently replaced it with the PS Anti-Glare shield. I didn't like the IS because it had a rubbery texture and I couldn't slide my finger across the screen.
I love the PS. The screen does seem a little fuzzier, but not enough to bother me. Fingerprints are pretty much non-existent (as was also the case with the IS).
To the poster who pointed out that the PS didn't come with any type of an installation kit: it's because there's no need for one. I think I've read the PS is held on by static cling.
I had mine installed at their Burbank store (for $5). The girl first cleaned the screen, then peeled off the entire backing off the PS. She lined it up at the bottom where the button is, then just slowly let it lay down on its own. When a bubble appeared, she just lifted the PS up and used a piece of Scotch tape to dab that spot. (Lint is what causes the bubbles.) She only came across one bubble when doing mine -- took less than a minute for her to do it from start to finish. (Mine had had the Zagg IS on since day one.)
Then she did my son's. She came across quite a few bubbles on his

, one she couldn't get rid of no matter what. She ended up having to get a second shield, and that one went on without a hitch. (His hadn't had a shield.)
(FYI: Unless she could see something on the screen, all of the dabbing was done on the shield -- which probably picked up the lint off the screen.)
I have no idea how the SGP that you're comparing the PS to is installed, but if it's anything like how the IS is installed, there's absolutely no way I would even attempt it (what with all the liquid, squeegee-ing, etc.). As long as you can get the bottom lined up correctly on the PS, all you need is a piece of Scotch tape -- it pretty much installs itself.