We were not involved in the early testnet for HF 20, we will be making efforts to try to be involved in future major releases (the coming SMT enabling hardfork for instance).

We implemented 0.20.0 as soon as it was publically available and then spent the next days downgrading and upgrading along with all the other witnesses and node runners.

Overall it was a good experience (for us) as we learned a bunch about appropriately running a witness, and quickly reviewing and implementing updates.

Plus replaying is just so much fun ;)