Hi Tony,
I posted some of my experiences on linked IBKR trading in a recent thread. Let me know if you have any specific questions.
One other edge case I should highlight is if you do any other trading or hold other positions in the linked account, these would need to be manually reconciled. For example, in one of my linked accounts, I was holding an ADR that was delisted. The position no longer was visible on the p123 side, and I had to enter a manual journal transaction in p123 to remove the market value of the position from my account. I had considered writing some covered calls for some of my p123 positions but was worried I would create a manual reconciliation nightmare (having to create debit/credit journal entries as the options were sold/bought). I still may give that a try.