I haven't seen that yet - thanks for the hint. (I knew I had to check it out someday but then i forgot to)
Although the user-switch in developer-support is quite useful it does not provide some features that I needed and added to the demo-login package, so it is not a complete duplication of effort: first, demo-login allows for unattended demonstration installations where for some reasons you do not want to allow the tester to become site-wide admin or some other privileged user. Second - the ability to add some explaining text to each account, so that the testing user knows what the account is supposed to demonstrate. This is useful for demonstrations that include different users with very specific different roles, e.g. in a particular customization of a workflow.
Btw, I found a problem with the developer-support user switch: it replaces the two procs ad_get_user_id and ad_verify_and_get_user_id with it's own implementation, but not the behaviour of [ad_conn user_id], which is used quite often in the toolkit (and seems to be the preferred way since the both procs above are -deprecated).
A possible way to fix this would be to overload ad_conn in acs-developer-support-procs.tcl as well. Any better suggestions? (I've entered a bug in the sdm for that.)