my friend has one of these i think, running next to an FX5. im not sure how big his tank is, but its about 5-6ft long, about 4ft tall, 1-2 feet wide bowfront, and the 2 filters keep the water in pristine condition. he works away for 2-3 months at a time, so needs his water and filters to be in top condition while hes not there, and they do the job perfectly. his tank has LOTS of fish in it. im not sure what the readout is for. i know he can set the flow rate, and i think maybe it tells him when it needs cleaning, i dont know ive only really looked at it once. it was however the easiest cannister filter to clean ive ever seen. i think it has 3 cartridge inserts or something, that just pull out and click back in, doing one at a time. they are expensive though. also a lot quieter than the fx5 was, and smaller.
whether they're worth it or not i dont know, i dont know what they cost. but he has loadsa money so it wasnt really a concern for him, he just likes expensive things.