Fake Intestines????

PRO:
1) Nothing moves and plops quite like organic material.
2) Intestines from a slaughter house (well cleaned and sterilized for safety - get rid of all of the bacteria) look and move exactly like intestines - a pig's intestines, but close enough and graphic nonetheless.
3) No sculpting, molding, or casting required, just clean and use.
4) Very cheap.

CON:
1) Health issues - real organs will rot sooner or later, and must be cleaned of bacteria initially for safety's sake. Even ground beef or liver will go bad, so biological materials must be fresh.
2) Refridgeration - keeping said materials fresh. There was a hilarious recounting of the problems Tom Savini had on the shoot of "Day of the Dead" with the pig guts he liked to use.
The little frodge they were kept in somehow became unplugged whenb they broke for Xmas. When they came back they had to shoot the scene where Joe Pilato is torn in half. The guts were stinking to high heaven, but they had to get the scene shot. On a real (even very low budget) picture, losing a half or a whole days's shooting can break your budget or destroy your schedule, require new permits, and create major havoc. There is on-set video footage of people wearing respirators, masks, etc to deal with the overpowering stench. Pilato says he was actually fighting against retching while he was delivering his lines for that scene. Funny in the re-telling - but not very funny in the middle of it.
3) Some people find the real thing just too gross to use in any way, or are animal lovers, etc. According to his book, Savini's stunt person (& friend)Taso Stavrakis (sp?) insisted on personally scrubbing the stuuf before he would let Savini put it under a chest appliance worn for D.O.T.D.

Latex/Silicone/Vinyl
PRO:
1) A good sculptor can create a near perfect replica of the exact size the organs would be, or exaggerate them to any extent the director/art director wants. A friend of mine was asked to scale up a human heart 1 1/2 times for Weird Al's "Like a Surgeon Video" by the art director. Unbeknownst to anyone, the video's director hired another artist to create a more cartoony style heart prop. The director (of course) went with his guy. Them's the breaks.
2) Plenty of identical duplicates can be prepared for multiple takes.
3) Synthetic props can easily have bladders/effects devices glued inside them for pulsing, bleeding, or other effects.
4) Long shelf life, can be prepped at the start of pre-production and tossed on a shelf.

CONS:
1) Expense: some of the materials can be pricey.
2) Time: It takes time to scult, prepare for molding, make a mold, clean the mold, and run castings through it which need to be cured, removed, trimmed, touched up, and colored appropriately. However, once molds are made, the time factor switches to favorable for producing a lot of something.
3) Movement: Only silicone compounds will move the same as real guts.

Savini likes to use rubber guts wrapped around a few large real intestines. Everybody has their preferences, experiment a lot and you will eventually decide what works best for your particular preferences.