It's one of the few systems that is constantly getting new features, very flexible, and high quality components. Yes, it's probably the most expensive, but i have way more invested in track and trains, so a one time cost is not too bad.
Basically their philosophy of adding features and considering customer feedback is head and shoulders above anything else I can buy.
I actually have 2 of the MX10, so that gives me 40 amps to distribute around the network (since you asked about "huge" layouts), so this allows me to have many locos on at the same time, since sound cards draw current while idling. I have a double-ended switchyard, so this capability of high current allows several locos to be active in the switchyard, and still have plenty of power for a couple trains on the mainline, which does indeed have some nasty grades, often a large train will pull 10 amps on the ruling grade, for about 60 feet.
Anyway, while not huge, I have had to work to find high current components, handle fair distances for wire runs, and need a large wireless coverage area, and with the house in the center it challenges other systems to perform, I previously used NCE, and had to have 3 wireless base stations to get coverage.
Hope this answers some of the questions you raised...
Greg