My plan was keeping it in a reservoir and having 64 of it in each jar. What's the limit on how much essentia can be kept in a reservoir?
So, from the official wiki;
"Similar to warded jars, essentia can only be received or drained from one side, but unlike the jars, the block's connection can face in any direction (and be changed with the wand). A special feature is that, like buffers, the reservoir is able to store 2 or more essentia types.
The Essentia Reservoir can store a total of 256 points of essentia total, in any combination of aspects.
Reservoirs cannot be drained or filled by hand (right-clicking with or without jars, or glass phials). Golems can work with them, but with some limits -- they are treated as non-jar devices, so they have priority over jars and the golem may ignore other marks if filling a reservoir.
The Infusion Altar (or essentia mirrors) will still drain essentia out of the reservoir just like it would for warded jars.
A further complication for using them in piped systems is that they only have 24 suction, so almost anything else can drain them unless buffers or other protective measures are used."
The issue I have with the things is that they still have the "Only one side can be a output/input side" that jars do. This makes things really hard to automate with anything but golems, which can cause lag of their own because they're entities with pathing. If you try to use the basic essentia pipes, this can back them up horribly and screw up your entire system. Now, in the Regrowth thread people have made some cool and workable setups with the reservoir/jar method, but I think most of them are Infusion Altar only, with other things needing your attention and work.
I'm also not sure how to mark the things. The wiki page doesn't reference a method of doing so, and I'm inclined to think that the normal jar labels wouldn't work. I'm sure it can be done, and it probably looks amazing once it's put together, but I haven't tried to myself so I can't give much more advice than this. XD