I'm not saying you need to be at 10.0, I'm just saying it's less tedious to edit sets because System Manager doesn't toss up a thick Windows Manager Lite.
On my SMGR 7.1, if I edit an endpoint on a IPO 9.1, I get Windows Manager Lite open. If i edit a 10.0 phone, I get Web Manager within the System Manager.
I'll say this on the subject: it's a great idea and with enough pain, you can make it work. I've found Avaya's efforts in this to be very disappointing. When you talk about System Manager, you're talking about a Java application server with all sorts of management tie-ins - it can manage Aura Messaging, Session Managers, CMs, CS1ks, CallPilots, etc. There's no one guy who does all of that. There's a System Manager core team responsible for the guts of it, and each product house at Avaya ultimately owns their plugin. With everything going on with IP Office, I feel their development efforts towards SMGR integration have been lackluster at best.
You want real world feedback?
See the attached picture. I promise you my system names are consistent and the stuff I blanked out is the same on every line. When my MACD team was having trouble and I was helping them out, I absolutely flipped my lid when I saw what they need to do.
Basically, when I need to click a drop-down menu to pick which IPO to provision a user on, that drop-down list IS NOT IN ORDER! As in, if you have hostnames IPO0001, IPO0002, IPO0003, etc, that dropdown will never actually list them in any order. So you get carpal tunnel and tire out your eyes scrolling through a list looking for a needle in a haystack. That's the level of attention to detail you're flirting with!