[duwip]

Yep, it would seem that KISSMetrics has a better implementation where aliasing can be called several times (as stated here: http://support.kissmetrics.com/apis/common-methods.html).

The fact that it links accounts retro-actively though can be dangerous, in the scenario of publicly-accessed devices. I'll have to admit though, this is not the common case.

I guess my personal gripe with what MP and KM are doing boils down to: if you can't infer stuff about who is visiting my website, be honest about it and don't.