So, the main reason we're using libev is that upstream krb5 uses libev. I think they do because libev is a smaller more self contained code base than libevent, and because honestly the KDC isn't normally a performance bottleneck, so it doesn't much matter.
That said, I think libverto in Debian should support all the options, and certainly should support libevent. That won't make things easier for Ubuntu really, if they want to avoid building libverto against libev, but it will let Debian users use libevent if that's what they want. I'd love a merge proposal that turns on libevent and leaves libev present, and will eventually try to get to that myself if you aren't interested in submitting that.
