At this time the RE NXT search bar uses first name, last name, or first line of address. When I search for a profile using the first name, it gives some suggestion to choose from, however, when I am trying to locate a profile using a middle name or spouse's name there are no suggestions given, and the possibility of creating duplicate profiles increases.
When I run across this issue (including with hyphenate/compound last names), I may add up to a dozen aliases to a single constituent if they have a first, middle, compound surname, maiden name, and different nickname/preferred name. But I can probably only catch a small percentage out of thousands.
The non-power users I've watched aren't familiar enough with database search precision to realize they need to try searching multiple ways if a constituent doesn't show up on the first search.