I've had the Thunderbolt, Charge, and Bionic on Verizon. I'm back on my iPhone 4 right now. I would have kept the Bionic, but its screen was unacceptable for a $300 device, but that's a different story. Point is, I've used the best 4G devices that they have. The speed is undeniable. "Just a few seconds" adds up throughout the day.
However, I'm pretty sure that at this point, the chipsets used require two radios to support LTE on the Verizon network. I believe this is why we are seeing all 4.3" devices so far. Strike one against the iPhone 5 having LTE.
The battery life was also inexcusable with stock batteries. I see people posting on forums that they can easily make it through a day with their 4G phones. They must just let it sit there idle. I am in a 4G area where I always get 3-4 bars and even with moderate use (texting a lot, and checking emails and facebook at work, along with a game or two on the *******), none of the phones could make it through the day without a charge. The extended battery on the TBolt allowed me to make it to the end of the day with about 20% left, but it made the phone a complete brick and even bulkier than it was to begin with. Strike two against the iPhone 5 having LTE. As a side note, I do understand Apple has some magic up their sleeve by making a 1500mAh battery last as long as it does in the iP4 (compared to other android devices I've used like the Incredible and Fascinate), but when I look at the usage statistics on my 4G devices, the 4G radio was sucking a LOT of juice even when the phone was idle, and I don't think Apple can do anything about that at this point in time.
Would I love LTE on the iP5? Yes. However, I just don't find it practical for Apple's approach on their products right now. Battery life is key, and one of the main reasons I go back to the iP4. I get the slimmest smartphone on the market with by far the best battery life. Unless Apple knows something/can do something that no one else knows about, then I doubt we will see LTE in the iP5. I would not want it at the cost of battery life. However, hopefully the technology will improve over the next year and we will see it in the iP6 when battery issues are taken care of.
Also, to those saying LTE is insignificant/not worth it/doesn't make a significant difference, you really need to play with a device that has it. It really is amazing how quick it speeds up everyday tasks on the phone in ways that you wouldn't think of without actually using it. However, even with all the praise I give it, I still don't find it beneficial when it's killing every phone that has it within 10 hours of even the lightest use (and in some cases even less).
Just my two cents.