Originally Posted by JerrySTL

There won't be all that much difference. The biggest consideration is that you'll need a new chain either way and probably a different rear derailleur.

You may be able to go to an 11-28 cassette without a rear derailleur swap, but probably still need a new chain unless you are very careful. If you go big-big gears without a longer chain, you could do some serious damage to the rear derailleur.