Ability to segment on matching/non matching evar values

[#1]

It would be great if we had the ability to segment visitors based on multiple value evar/prop instances.

For example, I want to know how many of our users log into multiple accounts on our site, i.e. how many visitors are associated with multiple userIDs.  Something like:

WHERE evar instances is > 1

AND

evar values DO NOT MATCH 

[#2]

A workaround (although non-scalable) would be to create segments with multiple eVar combinations (Visit where eVarX=Y AND eVarX=Z). But I could see this as being very useful.