The more I delve into Live, the more things I find that are inexcusably missing. The latest: if you have a midi track that output of which you want to route to a separate midi track which has an arpeggiator as the first device you simply can't do this!
You can select the track and then when you go to select the device on that track, the arpeggiator will not be in the list. That is just plain RIDICULOUS!