Personally, I dive a KISS, and I am weighted such that with my gear still attached (torches and stages) with the counterlungs full I am neutral. So that's one thing to forget about.
When I am diving with OC divers or even most Rebreather divers I tell them to just turn the knob and bail me out. You can then see I am breathing and lift me. I run the BOV from my offboard gas which means you've got a lot of gas before you even need to think about gas switches etc. In reality, I wouldn't expect a buddy to blast through their deco to get me up and just send me to the surface along with as many yellow bags as they can find so the surface support is on their way.
I would advise lifting me anyway you like, front or back, same as you would an OC diver.
I remember my regular buddy asking me the first time we talked about the KISS what they can do if there's a problem. In reality I said there's 3 things I want to avoid - High ppO2, low ppO2, high CO2. All three will either be dealt with by me or will result in turning that knob in my mouth. This is made easier because I have an old KISS BOV with the knob right on the front where everyone can see it. I have been thinking about getting another knob made out of luminous pink with a big on/off sign on the front.
Having dived with a large number of inspo divers lifting them isn't so easy. With a large amount of potential lift in the counterlungs there is this to think about, plus some units don't have BOVs, so all you can do is keep the loop in and lift and hope they're breathing. Not such an issue with an ECCR as they'll (as long as the unit is working) keep them on breathable gas. One of the reasons I suggest people bail me out is to guarantee breathable and useful gas, plus it is far more familiar for most. I find even experienced Rebreather divers have done far more lifts on OC divers than RB divers, something which I haven't seen much in RB training courses. I think there would be a really good opportunity for someone to come up with an RB rescue course, even OC buddies could come along and pick up the skills they need to make sure they can get you to the surface.
Hope this helps. I find the best thing to do is ask the user how they want treating if it hits the fan. Most have explained what to do to many people before.
Digs.