Hib,
So does the Z06 ride like the new GS will ride;
No one knows, yet.
a little more rough even with MR?
I'm going to guess pretty much the same
And does the base Stingray with Z51 fall into that same category of rougher ride?
A Z51 w/o MR is more stiff and harsh than a base car. A Z51 with MR is not quite as stiff and less harsh than a Z51 w/o MR but still more stiff and harsh than a base car.
It's hard to find a Z06 to buy let alone be able to go and drive one. Ideally, a guy should drive a base, Z51, GS and Z06 and then make up your mind. But good luck on that unless someone knows where a guy could actually do that?
I agree with you there and the dealer network wouldn't be inclined to make all three available as they'd sell less options that way.
That said, I think the choices are fairly easy.
If you want a 650-hp car, then the Z06 is your choice and, if you find the ride too aggressive, well, you'll have to live with it.
If you're content with 460-hp, then you have to decide what kind of driver you are. If you don't care about really aggressive driving but you do care about having responsive handing, a nice ride and having the Corvette experience, then a base car is the way to go. If ride, above all else, is paramount to your Corvette experience, buy a base car with MR.
If you're an aggressive driver on a budget who isn't bothered by harshness, buy the Z51 w/o MR. If you are an aggressive street driver but you only will accept a modest level of harshness and you're willing to spend some money, buy the Z51 w. MR.