Hi Scott,
Glad we were able to connect over a call. Just wanted to follow up on your note on Topliners as well - generally the usage limits we've outlined are a best practice to ensure optimal performance. Having said that, for many of the use cases that you were looking to address with custom objects, we are developing more productized (and scalable) ways to accomplish the same thing e.g. support for intentional duplicate email addresses (closed beta).
Best,
Taha