Well, we have two and the people we farm for have 3.  We don't have any problems with the sweep augers, we make sure the gearboxes are full of grease before we start, and then half way through the season if time permits.  Been lucky so far.

Like any flighting it wears out but shivvers is a littled heavier than regular flighting so it does last longer.

We have the older system and I hear the new ones with the better floor and big fans will dry more grain.  In 22-23% corn the new systems in 36' bins seem to keep up with an 8 row head in 180bu corn, might not be able to run 12 hrs but you can put in a good day.  We use 3 systems most of the time and sometimes a 4th  when the corn is really good or moisture is high, (5th unit is too far away to use all the time, only use it when we harvest that farm),we run an 8r head. 

If you decide to put in a shivvers put in another bin close enough so you can use it as a holding bin.  Depth of grain in a shivvers unit will slow it down a lot, if you can keep it to 5' max it will dry a lot quicker.

If I were do it again I would put in a holding bin big enough for 2 days worth of shelling, then a continuous flow dryer.  Have never been around one but seems they would work pretty good.  Those of you that use them let me know how you get along.