I've pretty much decided to skip the iPhone 6 and stick with my iPhone 5 for another year. One of the new features in the iPhone 5 two years ago was LTE or 4G. But sadly, even though I kept my eye open for it when roaming internationally, I've never seen "4G" in the status bar of my iPhone 5.
After the Netherlands implemented net neutrality in 2012, prices for mobile data went up a lot, but I'm grandfathered into a cheap unlimited plan from KPN that I'd have to give up to get LTE. Also, KPN uses LTE frequencies that the iPhone 5 doesn't support, so I'd have to switch carriers.
So what I did instead was get a prepaid SIM from Vodafone NL. The SIM is only 5 euros and they helpfully cut a microSIM to nano size at the Vodafone store as they were out of nanoSIMs. The SIM includes 5 euros of credit. You can buy additional credit in a variety of ways, including at super markets and through the My Vodafone app with a credit card. (Although it seems the app is only available in Dutch.)
By default, you only get 3G data. Helpfully, you get 50 MB that you can use in the first week for free. If you want 4G, you have to turn this on by buying a "blox" for 5 euros for a month. (Using an SMS message or the app.) In the residential neighborhood where I live, I got 3 Mbps down / 0.26 up with Vodafone 3G:
4G was much faster at nearly 12 Mbps down and 5 to 6 Mbps up:
However... with KPN, I get 14 Mbps down on 3G! And I've seen as much as 5 Mbps up on 3G, too. It does look like the Vodafone 4G goes much higher but has trouble sustaining that speed while KPN 3G is pretty much maxed out the whole time:
So I guess I'll have to retest in the city center where presumably, the network is denser. Also, remember that the iPhone 5 GSM model A1429 is limited to LTE bands 1, 3 and 5 (2100, 1800 and 850 MHz) while KPN uses 800 (and 2600?) MHz, Vodafone mainly 800 MHz and 1800 MHz to provide extra capacity, and T-Mobile is only on 1800 MHz. So a phone that also supports the 800 MHz band (such as the iPhone 5S/5C/6/6+) would probably do better on the Vodafone network, and also be compatible with KPN.
One complication is that the Speedtest app uses some 40 MB data to test the speed of the LTE network, and probably even more if it's faster than the 12 Mbps I got. So I burned through my 50 MB free data. I am then supposed to get 100 MB a day for € 1, but that didn't happen, so I ended up paying € 4 for a few dozen megabytes at the "regular" € 0.15/MB rate. Of course I could have avoided that by buying a GB worth of data that's good for a month, but that costs 15 or 20 euros.
So it turns out that the iPhone 5 does in fact support LTE. And Vodafone prepaid is a decent option to get LTE speeds without a contract, although it's annoying that you have to be really careful that you're not going to end up paying that € 0.15/MB rate or you'll burn though your prepaid credit in no time at all. They did send me a text message after I had used up 40 of my 50 free megabytes and then another when I'd used it all up—a few seconds later. In hindsight, I should have checked if I could get something similar from T-Mobile NL, because their 1800 MHz LTE network is going to be more robust because that's the only LTE band they have. Oh well.