Gland seals? I assume you are speaking of cartridge vs component seals. Please elaborate on this. Good place to look for information on mechanical seals is any seal mfg. Call your local Flowserve or John Crane facility.
Goulds Pumps, has in their Pump Manual a pretty good section that reviews both the stuffing box type seal and the various types of mechanical units. It's four pages, send your fax number to me at Pileser@aol.com and I'll fax a copy to you.
the Fluid Sealing Association (fsa.org i think) is excellent. also check out mcnallyinstitute.com . try to stay away from indivual manufacturers due to their bias.