Ed, whether you use a 2 slot, 5 slot or standalone makes no difference. You use the same line cord and the ground connection is a green screw on the processor itself. That supplemental ground is more a UL/NEC issue because if the line cord is pulled it leaves the system ungrounded and the premises wiring floating, possibly at the same potential as the CO line wiring that is also on the system.
I have written about Partner grounding several times. Because the designers dropped the ball by not connecting the green ground screw within the module with a piece of wire directly to the power connector ground at the rear of the module, (instead they used a common ground trace on the PC board) any difference in potential between the line cord receptacle ground and the supplemental ground can destroy the module. That's why if you do use the supplemental ground (and I pretty much don't) it absolutely must be connected to the same point as the line cord ground. You can't trust cold water lines, building steel, etc. as the Avaya documentation suggests. There might not be a problem when you install the system but I've seen processors destroyed several years later when things change.
As for the general longevity of Partner, I regularly see systems (Partner Plus and Partner II) over 10 years old. Matter of fact I see National chains like Old Navy and Crate and Barrel using refurb Partner Pluses and MLS phones even for new installs. For most small business even the older systems provide more features than they will ever need.
And no, I have not noticed any decline in quality of Partner (with maybe the exception of the phones) that would lead me to believe that a new system, properly installed, wouldn't last 10 years or better also. Matter of fact I believe that the power supplies that were the usual cause of a modules demise have been improved and the 5 slot carriers now provide better heat dissipation than the original.
It's very true that much depends on the environment and the steps taken to protect the system like protectors on the CO lines and a surge protector on the power. Of course much depends on whether those are quality devices and installed properly too.
-Hal
