In the process now, as we recently did the switch. Some initial comments:
- you should still have a waterfall in addition to the bidding, so that the winning bid can compete with high ecpm targets you set in the waterfall
- only a few networks have no-sdk solutions, so you would probably still need to add plugins from the major networks
- expect some time to establish relations with the no-sdk networks, as they might have a time consuming approval process (it's not just plug and play)
- bidding seem to deliver better ecpm when looking at average ecpm
- open bidding looks promising, however not at the point where you can set it up and leave it be, still requires monitoring and follow up
Best of luck!