Adding to that list:
7 - if you have a power failure, the controller can delay turning on your skimmer for 5 min (or whatever time you choose), so you don't overflow it.
8 - use a DIY water sensor (costs almost nothing) to turn off return pumps (or other) if there is a problem.
9 - send you emails on any condition you want, like power failures, temps too low or too high.
10 -monitor your power consumption.
11 - control ATO for your sump.
12 - control your dosers.
Etc, etc,...

On a note of convenience...I can even do a 50 gallon water change using my Apex app on my iPhone and I don't have to get off the couch :)

Pumps old salt water out directly to a drain, open and close a few solenoid valves, pumps new salt water from mixing station back to the display.

No pails, hoses, or towels! It was worth the set-up costs. One day later when the RO/DI refills the barrel I pour salt mix in and I'm ready for another.

I'd love to see some pictures of your setup

Sent from my Nexus 7 using Tapatalk HD

I ran my tank for 10 yeas without a controller, I think it's a luxury item you should pick up once you've spent all your good money on things you really need :) It's nice to have access to my pumps and lighting, etc, from my phone, and it's great in that it runs my lighting and pump profiles, but really not a "must have" item. If you've got an extra $500, sure, they're nice, but that's a lot of livestock you can add.

A controller was the last piece of equipment I bought, and it's been worth every penny. I have a really small space in my cabinet to work with, and it was a crazy rats nest of wires and cables, and i dind't have nough room for a dedicated switched outlet for everything, so I was constantly having to unplug crap when I wanted to turn something off. Having the ability to turn off any device, powerhead, or pump in my system without having to reach in there and mess with cords alone was worth it. Because I didn't need to access the plugs anymore I was able to put the powerbars in the studs of the wall, which totally cleaned things up.

Also the feed cycle programming is brilliant. I've got a schedule just for cleaning my skimmer and feeding my fish. All it does is shut down my return pump and skimmer for 5 and 7 minutes respectively, but that alone has made feeding so much more efficient. By the time the return pump kicks back on there's no more food left in the water column so I know none of it's getting wasted down the overflow.

Also, having the Apex control the temperature gives me way more peace of mind. When you've got more than one heater in your tank and you know they're not calibrated exactly the same, it's so much nicer to just turn the dials on the heaters all the way to their max setting, and then use the controller's independent temperature probe to either give them juice, or cut them off.

I'm under-utilizing my Apex, next on the wishlist is the wireless module so that they can control my vortechs, and a pH probe.