Vitamin G,
"How do they compare?"
The Classic Turret is a superior product.
"DO they compare?"
Yes in that they are similar in operation. But the older model lacks design improvements (such as spend primer handling and cast iron construction) the new one has. Therefore, the new one is cleaner and due to it's heavier construction, has a much greater range of cartridges it can load, including large rifle cartridges.
"I'm going to be ordering one in the next few days, and it seems as though the old styles comes with significant savings in the kit form, since it includes the autodisk and a set of dies."
You'd be better off taking your time and selecting a bit better stuff. If you do so, your reloading experience will be much more positive. There's a sticky for new reloaders listed at the top of the page that lists quite a bit of the product line offerings of the various manufacturers and talks about them. Were I you, I'd use the list of "stuff" in the Lee turret kit to help me pick out the items I didn't already have, but I'd buy the Classic Cast turret with all it's goodies, since it's just a much better press for not much more money.
"I've been loading single stage, and want something faster, but i'm not interested in a progressive."
Once upon a time, I upgraded from a single stage to a Hornady Lock N Load progressive. Had they had the Lee Classic Turret available then, I would have purchased it. It offers lots of inexpensive versatility as a die set and a turret is all you need to change most calibers over.
"I want the auto-indexing feature also. Is there a difference in the efficiency of the primer catcher?"
The auto indexing appears to be a bit more durable on the Classic Cast and the primer catcher has a tube that directs spent primers into a bucket or trash can, thereby keeping your press much cleaner than the older turret, which lacks this feature.
"I know the contruction is a little more solid in the classic (new), but are there any major differences other than that?"
The Classic Cast is of course, cast iron. The older turret is aluminum. The big advantage though, is the compound linkage the Classic Cast offers. This allows you to handle much larger cartridges. In addition, the press is cleaner and the auto advance mechanism tends to be much less problematic.
"Are you saying that the riser is basically pretty mandatory for the classic cast turret, even if I'm using LEE dies?"
If you purchase the Lee Safety Prime (which gives you a significant speed advantage and you should get it, regardless of which press you end up with, it'll work on both) you'll need to get a riser (a $6.00 steel part) in order to raise the powder measure up higher to clear the safety prime.
BTW, speaking of powder measures, the kit comes with the Lee Auto Disk powder measure. The Lee Pro Auto Disk is a much better powder measure and is the one I'd advise anyone to get.
Here's a list of stuff (the luxury list, not the basic) for the Lee Classic Cast with Lee part numbers:
90064 Lee Classic Turret press
90997 Lee Safety Prime Kit, for large and small primers
90269 Extra four hole turret
90195 Double Disk Kit (for large powder loads, luxury item)
90429 Pro Auto Disk powder measure
90041 Auto Disk Riser
90762 Adjustable charge bar (luxury item)
A set of dies of your choice. You'll need a extra four hole turret for each set of dies (unless you just love setting up dies).
Since I don't know what you already own, I'm not going to list any of the extraineous reloading equipment, but the sticky should help you pick that stuff out.
I hope this helps,
Dave