No no no no no everybody..

Tango+ is used to compete against transborder American carriers -- it has advanced seat assignment and 100% status miles (used to be 50% status miles) -- this is in line with American carriers. They couldn't use Tango because you get no status miles and no seat assignments, so this made sense to have Tango+ the cheaper (and competitive) option... this is the reason why Tango+ is cheaper than Tango.

This was stated by Empress a few times in past threads, as well as at the YVR DO.

http://www.flyertalk.com/forum/showp...7&postcount=71 (for the newbies, Fun is the old name for Tango+)

But also, keep in mind what exAC said above... the cheapest Tango is still cheaper than the most expensive Tango+, but for the most part you will see the cheaper option in most cases as the fare classes tend to align themselves with others.