Well for me personally I am going to decide once we get LTE here in NYC, and see if it reaches my house. In my house I get like 3 bars max for sprint and wimax is 2-3 houses away(grrr lol). So until I can confirm LTE in my area there is not much point in upgrading my sprint line. So far I am using my verizon line more then my sprint line (though I have a keyboardless droid charge and I don't enjoy it as much as I do my epic, using a none keyboard phone kills all the enjoyment other then watching movies on it)
Now as far as the radios go, it depends what your getting. For example, the epic radio and gs2 radio were not that great, the radio on the gs3 I hear is pretty good. Also from what I hear samsung makes the best LTE radios, (my verizon samsung phone does pretty good on LTE).
I think the reason why samsung has poor cdma radios has to do with the qualcomm chipset they use for cdma. Most qualcomm processors have cdma radios built in, but none qualcomm processors have to get a qualcomm motherboard chipset with separate radios. Samsung unfortunately for the Epic and GS2 chose to use an OLD motherboard which probably why the radio performance is what it is.
By the way I posted a much more detailed spec sheet directly from motorola:
Motorola PHOTON Q 4G LTE Fact Sheet - Fact Sheets - Motorola Mobility, Inc.
As far as seeing a keyboard phone for HTC, I kind of doubt it. Sprint plans to release 3 keyboard phones. One from LG, one from Motorola and one from Kyocera. The Kyocera is a low end phone. The LG from what I remember is better then the kyocera but worse then the Motorola. If sprint is dishing out 3 keyboard phones I doubt they will have room for a 4th. Too bad none of the keyboard phones are at galaxy s3/One X level. Though this motorola comes very very close, it fails at battery size and resolution though.