Im not a fan of items like portable tanks from TE3 myself, i think they are very cheap compared to vanilla buckets. 1 metal ingot, holds 8 buckets. Its not balanced vs buckets at all. Ideally id like to see things that give greater utility cost noticeably more, or have some other drawback.
So that brings up Cells. 4 tin instead of 3 iron to hold 1000 mb of liquid, but... you can stack 16 of them into an inventory slot even when full. was this the idea behind them? To make a bucket that was stackable, and then make them a big more expensive to make up for that?
Now compare this to a low end portable tank from TE3, to hold 8000 mb of fluid in your inventory in IC2, you have to spend 32 tin. With a portable tank, you only need 1 tin (?) and 4 glass.
Does anyone remember if this is why clls were made, and why? To give you a stackable bucket, for a price?