Yes, I am. Pack can hold millions of files with no problem. One field in which it shines is that, aside from being fast at processing large amounts of data, it can process many small files much faster than similar tools or even many popular file systems.

About piping, it can be done, and it is on my list. I will finish features based on their popularity and making sense.

As Pack has random access support, you can choose a file in a big pack, and it can stream it out to the output. It is already able to unpack partially to your file system (using --include="file path in pack"); streaming/piping it would not be a problem.