Everything is working perfectly with one exception. I find that now, after making all of these adjustments, I must press the activity button to execute the commands (eg when I go from watching TV to watching DVD) I must now press the activity button twice to get the inputs and other settings/devices to switch over to DVD mode. Any suggestions?

Incidentally one of the reasons I ordered the One is that I think the buttons on my 676 are wearing out, ie I must press them harder and harder to get a response as compared to the OEM remotes. I know in this forum people have said that debris gets into the remote and you need to take it apart from time to time and clean it. I'm not sure this is an issue. Any thoughts? Thanks

Try increasing the inter-device delays on the devices that aren't responding.

Try increasing both the Inter-Device and Inter-Key delays. Make them both the same value in case the "criss-crossed" and/or "added together" bug(s) is/are still present.

I followed your advice re the delays and it solved the problem. I also reduced the "noise" that my extender was experiencing from the TV (and perhaps other devices) by re locating the extender receiver. That increased the efficiency of the extender.