Things wear out. You have to keep it lubed & clean. So yes, it is a set & forget for the most part, if you do not convert it to other calibers. Every caliber conversion requries some minor adjustments, so potential for things to go wrong. WHy I like the 550 for changing calibers often, it's just that much easier to get back up & running.
As far as the LNL goes, sure, if you must have a auto indexing press w/o a case feeder, then it is the only real choice over the 550. It is no faster though, just auto indexes. If you want a case feeder now or in the future, the LNL & 650 are the same price, well within $50 or so. The 650 comes setup for the feeder so you only need the bowl, $220. The LNL needs all the case feeder parts, so it's feeder is $320 +/-. Equipped the same, the 650 is only $50 more & a FAR BETTER machine. The priming system alone would make me buy it over the LNL. I have done about 12K rds on the 650 now, not single primer malfunction of any kind. I doubt many LNL guys can claim that.