yeah, everything works like normal, mine stops and starts drives on electric only up to about 20mph if i try to, just doesn't activate 4cyl mode. other than that everything is the same. I honestly saw no difference in mileage, there's a timer on 4cyl mode labeled oil foaming, I don't remember the max time it allowed it to stay on but it's in seconds. I did it a few days after I got it in the middle of a road trip, didn't see any mileage different up there, maybe some around town. there's also a guy that makes a manual block off plug that once you turn off the electronic side you can plug the oil passage way under the oil pressure sensor going to it to make double sure no pressure builds up and deactivates the lifters. but you can't do that till it's done of the tune side first. I've got the plug but haven't done it yet.
it's 2 credits to unlock the ecm with hp, which come with 6 preloaded, at least did years ago when I bought mine and then it's just a drop down box, it's labeled backwards for some reason, but they say it's how gm commented it in the code, so they left it. change it to enable and it disabled it. I already had it for my c6, so didn't cost me anything. I'm sure any tuner can do it for you, or they seem to sell well used with the 4 credits you'd have left. there's not a ton you can tune on these trucks besides that, you can cal the speedo for different tires, adjust the wot a/f target but no ve table for tuning over all a/f. which I though was odd, as I've seen one post somewhere of a guy doing a full air intake and picking up a mpg. if you had the ve table access you could do an intake and without 4cyl mode hack off the big extra resonator they added to kill the 4cyl drone and pick up another mpg probably.
no hybrid stuff at all, but I wanted to avoid the lifters issues, as I tend to keep stuff and don't really sell cars very often, this should be a around a long time. engine looks spotless inside from what I can see what a bore scope and I changed tranny fluid and filters the other day and it looked surprisingly clean in there. the tranny setup is really the only thing that worries me long term. hopefully it hangs in there.