I've never kept them personally, but we have both types at work. We have two four line pims in our 700 gallon display and they are FIESTY. They have to be because of all the BIG cichlids and marmoratus cats in there with them. The ornatus seem to be pretty chill, voracious eaters and very active.
They are also very attractive.
I have two four lines for 2 years. They were each 8'' long. Very long whiskers that look cool. Very active, easy to keep, easily to feed. Can breathe O2 directly from the water's surface. My two were inseperatable. I'd recommend getting atleast two of them. They're very social amoungst themselves. I kept them with a 8'' pacu and a 10'' oscar. They all got along great. The 4 lines would even come up to the surface of the water to get their fair share of food during feeding time. I highly recommend the 4 lines for anyone who can enough swimming space for them since they are so active.