Can the latest iPhone 5s be operational on both GSM and CDMA?

Question:
With a lot of controversial information available, ranging from 2011 to current date, there's no concrete information (that I could find) on the subject of what the new iPhone can really do. They sell 2 main models in the US, a GSM and CDMA version. The controversy is that the hardware is identical and the different models display that they function in every band. "GSM / EDGE / CDMA EV-DO Rev. A and Rev. B / UMTS / HSPA+ / DC-HSDPA / LTE Band GSM/EDGE 850/900/1800/1900; CDMA EV-DO Rev. A and Rev. B 800/1700/1900/2100; UMTS/HSPA+/DC-HSDPA 850/900/1700/1900/2100; LTE 1/2/3/4/5/8/13/17/19/20/25"

So what's the down and dirty? I have read that the Verizon (CDMA) iPhone 5c/5s comes unlocked and is usable on GSM also. You just need to change you APN settings to receive data.
Is there a model that can work on both CDMA and GSM?

Scenario:
I have been scouring the web for the past few days to help my boss find a good solution for a true 'World phone'. He travels abroad, and is looking for something that gives him a lot of options. I have found that the iPhone 5c, iPhone 5s, and Samsung Nexus i9250 all have a very wide range of operation, there internal antenna and hardware supports penta-band (or greater). But with so much different and controversial info I don't know what to conclude would be a good solution.

Any phone sold in the US by a CDMA carrier (Verizon, Sprint) that has a SIM card probably won't work with a US carrier. Those devices are designed to use the SIM portion outside of the US, where CDMA is practically non-existent. This may have changed, but since their main competition are two GSM carriers (T-Mo and AT&T), it makes no sense for them to allow those devices to work in GSM mode in the US, right?

If he travels a lot, it just makes more sense to have a GSM device. Frankly, any phone will work pretty much anywhere if all you need to do is make calls and send texts, since pretty much all phones cover all the necessary frequencies to do that in most of the world.

For example, I'm going to talk about my device, the Goggle Nexus 5 from LG. Here are the specs:

http://www.gsmarena.com/...5-5705.php

The 2G covers 4 bands. This will work pretty much anywhere. The HSPA+ and LTE bands (for 3G/4G) may or may not work in all countries, so it might be hit-and-miss. You would have to look up the frequencies/channels used by a foreign carrier to see if you'll get the higher data speeds. But there's always the availability of wi-fi, which is EVERYWHERE.

The problem with the iPhone is that Apple has made sure that the old "walled garden" is walled up really high for their phones in different countries. That's probably the LAST company I would purchase a phone from, even at home.