I believe that hop pellets and plugs are essentially just hops that are grinded and pressure molded. Given the amount of nuisance that whole hops have given me (clogged siphon hoses, yeast washing/rinsing, lost volume) would it ever be advisable to grind them up in a food processor/Vitamix? I could envision one of the problems being that some of the essential oils would 'stick'to the sides of the blender/food processor. I just have a ton of whole hops in my freezer and am getting tired of some of these problems that don't exist as much with pellets.
I think this is one of those things you just have to try out on some old hops. A coffee bean grinder might work better if grinding dry. Even if oils do come out, just use a spatula to scoop up all the hops and oil.
If you're doing this on brew day, you can use a blender/food processor with a little cooled wort from the first runoff to create a hop-paste. Use a spatula and then more wort to get all the hops out the equipment.