what are the advantages of installing a high output altanator vs stock and dis advantages if any?

You will have more charging capacity with a high-output alt. The question is, do you really need one? Bunch of kids running tv/movie/video games? In most cases, the stock alt has enough capacity to run extra equipment. It is when you add extra high-output lighting, big stereo system, an electric winch......

A HO alt will be slightly harder to spin (more parasitic drag on your motor) but nothing that youwill really be able to measure.

The choice is really up to you, and if you really need it, is it worth the extra money

A Suburban already has (sort of) a high output alternator. It is useless unless you have tons of electrical equipment.

I think you may have a over charging problem with your battery if you go higher than 45amps.Use two batteries for anything higher...ok.