can we cover the pros and cons of auto index?
I don't know of any real negative with the auto indexing if it works. I had large problems with it when I first started using the press. Hornady replaced the whole press twice before I finally got one that worked like it should. It seems the indexing is flawless or it does not work and there is no in between. I never did learn what the root cause was, but Hornady CS was great the whole time. In fact if CS had not been so good I would have returned the press about two weeks after it arrived.
There are some operations that need a single stage press like de-bulging .40 S&W cases and I thought the LNL could not be used as a single stage, but it turns out it's very easy to make it a single. All you have to do is remove two indexing pawls and that only takes a few seconds. Putting them back in and adjusting the index is also quick and painless.
If there is any negative about the press it is the learning curve. At least for me it took many loading sessions to learn how to properly operate the press and how not to break something every time. Sometimes the press will lock up (by lock up I mean the shell holder will not turn without a lot of force). When that happens you have to teach yourself to STOP don't force it or you will break something. When the press locks up it means a case is not in the holder correctly or is tilted, or a primer did not get completely removed from the case, or a primer did not get seated all the way. It is also possible to trash lodged under the primer punch and it will not retract which will lock the slide and cause the cam wire to pull loose. If that happens you must learn to STOP. If you don't you will break the cam wire bracket.
Another part of the learning curve is keeping the press clean. The tolerances of the moving parts are fairly tight and debris under the shell plate, or in the primer slide channel, or around the primer punch can cause all kinds of problems. I keep a can of compressed air by the press at all times and use it frequently.
The indexing positives are apparent the very first time you start to reload. Speed is the most noticeable benefit. I like to de-prime all my brass before I clean it up and I can de-prime a thousand cases in less than an hour. The operation is to inset a case and pull the handle - that's all. I don't have remove the case and I don't have to turn the shell holder plate.
The other, maybe more important, positive is auto indexing eliminates one hand operation each time you pull the handle. When loading a lot happens every time you pull the handle. The press has five stages, but seven different operations are performed every time you raise and lower the handle; re-size and de-prime, seat a new primer, drop powder, expand a case mouth, seat a projectile, crimp, and eject a loaded round. With all that going on it's easy to get distracted and forget to turn the shell holder plate by hand. If that happens you will get a double powder charge. With auto indexing that does not happen.