Carolyn has considerable experience with high dose kitties so there's not much I can say. There are certain physical characteristics associated with acromegaly, in addition to dose issues. If you want to see a SS where the dosing has been worked up, take a look at Shadoe's SS. Gayle is waiting on the "official" diagnosis based on lab work.
I doubt that there is much difference between Lantus and any other insulin when it comes to bouncing. It's a natural response of the liver to lower numbers. In many ways it's a protective mechanism. Because most of our cats have been diabetic for a while prior to their being diagnosed, their body has become somewhat accustomed to being in higher BG ranges. As insulin, or a cat's pancrease producing endogenous insulin, drops those levels, sometimes abruptly (and other insulins are much harsher in that regard), their liver, which stores glucose, panics and dumps glucose into their system to "protect" it from the lower numbers.
A few weeks ago, Jojo commented that the bouncing is actually a good thing. Given that a diabetic cat may have some functioning beta cells in their pancreas, if at the early stages of treatment, the numbers were staying low all the time, it would be putting undue pressure on those functioning cells. As a result, whatever functionality was there would cause them to burn out. So, in effect, the bounce takes that pressure off.