This is a common concern when buying a Vitamix machine. Do you really need the Vitamix dry container? The dry blades are shaped to push ingredients up, in order to minimize packing into the bottom corners. The dry container will fit any current Vitamix machine, including the “next generation” ones. (See this post for a comparison of the current models.)
I’ve heard salespeople selling Blendtec machines say that an advantage of the Blendtec is that it does not need a separate container to grind dry items, whereas with the Vitamix you “need to buy a second container.” It turns out that this is not true, and it’s just a sales tactic. The standard Vitamix container will do a perfectly good job of grinding grain, as I will show in the video below.
The real reason to get a dry container is that grinding very hard items like grains will pit and scratch the inside of the pitcher near the blades. In addition to the aesthetic “cloudy” marring of the container, the scratches make the container more likely to hold smells. You can get rid of lingering odors by running the machine with vinegar or a few drops of bleach in water, but it’s nice to not have to worry about that. I’ve never run anything garlicky in my pitted up dry container, but I did grind cinnamon in it a while back, and I can still faintly smell it.
Having a second container is also convenient because to grind grains the container needs to be totally dry, and if you made a smoothie in the morning the container might still be wet. Sometimes I end up using both containers for a single recipe, such as mega muffins.(Although if you just had one container you could dump the dry mixture into a bowl and then re-use the container.) If you are going to get a second container, it might as well be one with blades optimized for dry ingredients.
For these reasons the dry container is worthwhile, as long as you plan on grinding dry things like grain. But if you’re on a tight budget, you can get away with just using the single container, and possibly deodorizing it when needed. (Over time, depending on what you blend, your wet container will probably get scratched up as well, just not nearly as fast or as much as with grinding dry grains. I suspect that things like chia seeds in smoothies can scratch it, but I think that the scratching is reduced if you do not put the seeds at the very bottom, so I now generally add chia seeds to the middle of my ingredients instead of the bottom.)
I’ve always used the dry container for grinding grain, but this past weekend I decided to test a wet blade. I was surprised at how good a job it did of grinding 1-2 cups of wheat berries at a time, which I used to make pancakes and bread. The only difference I noticed was during the bread kneading I found the dough did not “lift” off the blades as much, but it still worked.
For the video I ground one cup of wheat berries for one minute in a container with the standard “wet” blades, and then pushed it through a sieve to see if there were any unground bits. There were a few, but they were small enough and few enough to not be a problem for my purposes. (In fact, when I used the same strainer on flour I ground for the same amount of time with my dry container, there were actually slightly more unground bits!) If you are looking to make a really fine flour you could stop the machine and stir the flour packed into the corners back in using a chopstick, and blend a bit longer; if you want it extra fine you could sift it.
Vitamix warns that you should not blend dry ingredients for longer than 2 minutes because the heat could damage the container. 1 minute to 90 seconds is generally all you need. I further avoid heating by storing the grain in the freezer so it starts the grinding process cold.