That is a loaded question!

Some folks have no problem with them, others have fried the guts inside them due to excessive heat buildup.
Seeing as am MB will go twice as fast as a bicycle was really designed to go, cooking the grease and guts is not surprising.
The general consensus is calipers are recommended. Disc brakes are awesome!
You can get by with a front caliper and a coaster rear brake (your "reverse" brake) if you keep your speed reasonable and plan your stops well in advance. Do not ride the rear brake long enough to overheat it, like going down a long hill.
Side pull calipers are marginal, v-calipers are good as well as center pull calipers.
Here's a link to an awesome site that shows a few designs and how to care and feed them:
Harris Cyclery Articles About Brakes
There are cheaply made disc brakes out there (read Wall Mart bikes) that can completely fail without notice, so be careful with those and get quality ones if you go that rout.