the more important question is IF they remember c3.xyz will they understand that they can type that in ad get to a website just like typing in c3.com or perhaps they are required to type in
www.c3.xyzThe "www" is not a factor in choosing a domain. Any domain
blah.oink can be set up to use both
blah.oink and
www.blah.oink (or
xyz.blah.oink for that matter) to address the same site.