jkust,
I can agree that traction control doesn't work as well as locking diffs or limited-slip diffs, but most of the basic vehicles have some form of traction control (brake based). I would bet you a dollar to a donut that a 2wheel drive Tahoe with an electric locker are slim, 4WD, slim still, but probably not as rare as a 2WD. I would argue a point you make about a locker, they are not design/installed for towing, they are designed to be used in slick, off-road situations (I would agree on a boat ramp being both those!). Both my Toyota's have lockers and they are limited to 4 low and below 5mph (Again, I would still say that's appropriate for a boat ramp, but a 2WD Tahoe will not have 4low or 4high for that matter!?). If I were given the option of traction control or electric (or pneumatic) locker in a boat ramp setting, I'd more than likely have the traction control. With a locked rear end on very slick surfaces you get both wheels spinning, then, that's the end of forward momentum as they just become 2 spinning, slippery skis! Where as with the TC one wheel would still be trying to slip and the other would stop and repeat...It happens very quickly (almost imperceivable?)
Used to have traction control on my Land Rover Discovery II, worked so well in the snow (I had 17" wheels with very wide tires) granted, it was all wheel drive, but very, very stable. I rented a GT Mustang (2005) in Boston over a Thanksgiving weekend, snowed the morning of...drove from Boston to Rochester with traction control, was surprised how very little slip I experienced...had no trouble getting around the secondary streets. I had previously owned a '97 GT Mustang without TC...when it snowed, I left it in the garage. I've owned a few cars with lockers and in snow, they're pretty much useless for hills/ice. They work great in rocks, mud, general off-roading and fresh snow, but ice...no way.
Anyway, most likely a moot point as he's most likely got unlimited slip rear end with (or without traction control). Just a point to consider!?
~Brett