Ben;
I actually requested a PEG following my mandibulectomy. I, like you am able to swallow liquids and am not even using my PEG except for medications that I'd rather not taste. The reason that I wanted it was to have a "plan B" for nutrition. Proper and adequate nutrition is very important when one's body is trying to heal and/or, endure chemo or other treatment. The actual procedure of inserting a PEG tube is really very benign. It is usually done under an IV anesthetic of some sort and takes a very short amout of time. While you are in a state of unawareness, the surgeon sticks an endoscope down your mouth into your stomach and points it at the front. In a darkened room, the light can be seen from the outside. This is where the incision is made. Then, the Tube is merely passed into your mouth, and pulled out the hole. There is a small, flexible "mushroom" on the inside that keeps it from coming out all the way and a little rubber keeper that keeps it from sliding back in. Aside from a little tenderness around the site for a couple of days, I felt fine after the surgery. The tube is not noticible. I ususally just tie it in a loose knot to take up the slack so it doesn't hang out from under my shirt. No one notices it. I simply flush it twice daily and that's the only time I really deal with it. When you don't need it any more removal is also quick and done during a regular office visit.
Personally, I wanted it in place in case my ability to eat does become more comprimised. Going in for any kind of procedure when you're weight is already in free-fall definitely adds complications and requires you to play "catch-up".
As others have stated, its a personal choice. I, admittedly, tend toward being a medical maximalist while others lean more towards the minimalist side of the spectrum. For me, PEG tubes have such a low risk and could possibly provide a real nutritional safety net that it was a no-brainer.

Just my $0.02

Be well!