For most shows, I run my tops (1 x 15" and horn) in full-range mode (i.e. using the full-range input); however, the top cabs are only producing around 100hz and up (subs handling everything else below) - crossover is a dbx-260. It sounds good and there's plenty of power, and guests/attendees/managers provide good comments on the sound quality.
Over the past many years, it seems that internal crossovers have greatly improved. I used to have to tri-amp because internal crossovers were crap, but now it seems any quality cabinet made in the last 10 years has a decent crossover. It it works full-range, I'll do it... if not, I have the option of bi-amping the tops.