I tested the changed RC costs of v0.20.6rc1 on real data here:
https://steemit.com/steemdev/@holger80/measuring-rc-costs-for-0-20-6

I used the patched rpc node: https://testbed.reggaemuffin.me/. As RC is non-consensus, testing works also when all witnesses run 0.20.5.

The RC costs were changed as inteded.

The RC costs of all broadcasted operations are slightly increased, as now the execution time is now included in the RC cost calculation.

RC costs for a vote are reduced by a factor of 2.5. RC costs for a follow custom_json OP are increased by a factor of 5.6. The RC costs of other custom_json operation is not affected.