Trade-off Triangle: Perf Index-Consistency-UX

Some constituencies are experiencing a trade-off as illustrated by the following diagram:

It seems as though they can pick two, but never satisfy all three concerns. For example:
* Org can keep their content consistent between their normal and AMP pages, and deliver a better user experience (e.g., by not using iframes for embedded content) - but their perf index suffers
* Org can focus on the perf index pieces and maintaining content consistency, but deliver a worse user experience
* Org can focus on the user experience issues and perf index, but the result is different experiences on AMP pages vs. normal pages.

We should define some good cases of this tradeoff and discuss with the AMP TSC

Start with the linked trade-off diagram and the examples in the issue, then review the AMP TSC context for performance, consistency, and UX concerns. The work is done when representative trade-off cases are defined and discussed with the AMP TSC, but the issue does not name files or tests to run.

Written by the indexing model from the issue text.