Poe+ With Built In Surge Suppression

Do they ever malfunction? Like not preventing surge induced equipment failures? Or ethernet errors under normal operation?

I'm asking just to gain more knowledge and compare my experiences with ethernet surge protection.

I like the thought of having equipment completely protected and never having failures due to surges of any kind.  But over the years I have kinda put it in the hands of the customer to make that decision. I have never tried the Ditek brand, but all the other brands either cause problems under normal operation with ethernet errors or not preventing equipment failure with surges. 

Is there a product available that can display and log voltage on each conductor? Then you could see if the device is actually doing something. For $50 I would think something like that could be made.

$100/camera run is a hard sell for me. Which might be why your shopping around. You can buy PCB boards without enclosure that look similar to Diteks for around $5. Ubiquiti has some in a nice enclosure for under $15 for single line surge protection. But I'm sure Diteks are better quality. If you are installing $100 cameras and trying to satisfy your consultant, I would go with the $10-$15 Ubiquiti. And stick with Ditek for the higher end equipment if they are working well for you now.

One thing I forgot to mention. I've tried both extremes of either grounded, shielded and surge protected to the max, and completely opposite using ungrounded, unshielded, without surge. 

I'm still undecided on which way is better. I've done a lot of work on communications towers in south east Texas (lots of lightning) for 15+ years. I've seen a lot of older unshielded cable, ungrounded equipment, with no surge protection mounted on a tower with equipment properly protected. The tower will take a direct lightning strike. The old stuff keeps ticking, the properly installed new stuff dead, including surge protection.

My non scientific unproven theory that I have seen work is isolate the equipment from the power grid as much as possible, insulate it from ground, mount it below the high point of the structure, and give the cable large service loops. The draw back to this is if the equipment outdoors takes a direct hit, then more than likely everything gets fried. But I've seen everything get fried that was up to code too. 

At the end of the day, it really comes down to a liability and safety issue. Nobody wants either of those two problems. But I figured I would share my experiences.