One thing I don't quite understand is that the stall speed stock was theoretically 1500rpm but it plainly does not stall at those revs. Mine is supposedly 1800 so treat this information as relative to itself only.
I have noticed that mine locks and unlocks a lot more than it used to although fuel economy is the same as it ever was even though I've gone from 189rwkw to 255rwkw. It doesn't unlock on cruise per se, just say you are cruising at 60km/h and then hit a slight incline it will unlock. To be expected really. It's kind of like having extra gears in between.
You wouldn't have too much power with a higher stally, just need better tyres.
The Valvebody upgrade (I think that's what you meant) is good because it will keep things cooler when shifting. I suggest you get a temperature gauge for your auto so you know what it's doing. I have just done this and it has given me a much greater appreciation of what is going on in there.