In House DVD Duplication Advice Please

Im relatively new to the DVD process and am looking for adivce from others regarding in house duplication. I use DVD Studio Pro, and burn on a pioneer DVR-104. I am limited to burning only DVD-R General or DVD-RW discs. Is DVD-R General ok to use as a master as long as the content protection devices are not activated? Does anyone have experience with DVD Duplication units? How does DVD-R General media hold up on these devices, and what kind of loss is predictable with discs that won't play in all machines? Is it necessary to use DVD-R Authouring or DLT for an in house dupilcation system?

Thanks in advance for any advice.