I do realize that all the radios are on the S4 chip, that's not the point. Even with the current generation S3s (Rezound, Sensation, etc.) they have all the radios on the chip as well. The difference is which are in use. It's one of the reasons you get better battery life by using 3G rather than 4G LTE. Now just because all those radios are on board doesn't mean all of them are in use. Depending on location, an international HTC One X is most likely using it's GSM, WCDMA, & possibly HSPA radios. Where the same phone for Verizon will be using it's CDMA, EVDO, & LTE radios. There's even a story that a few Verizon phones are going to have their global capabilities unlocked in an update. Some radios are locked by carrier, but even if it's unlocked, if it's not set for LTE, that radio won't be in use. The only way it will effect both phones the same is if it's set for LTE, I doubt anyone would set it to LTE if it wasn't available.
Sorry about the math error, I had about three hours sleep when I posted.
As far as the difference between battery sizes, the screen size will make a bigger difference than a few hundred mAh. I've had the Thunderbolt, Inc1, Inc2, & the Rezound. The difference in battery life between the Thunderbolt & Inc2 was big. Since I don't have LTE yet, the tbolt was set to 3g only, both have similar size batteries, the same CPU, ram, etc. On 3g with both phones, the tbolt got around 1/2 to 3/4 of a day, the Inc2 got 1 1/2 days. That .3" of screen makes a difference. While they lessened the amount of battery loss from the screen (like with the Rezound) to an extent, it's still a battery hog. Unless you mate a big battery with a big screen, or they come up with a miracle technology, bigger screens are gonna suck for battery life.