LTE Cat4 and Cat1 Comparison - Energy requirement?

[marinelad]

I'm looking to make the jump from 3G to LTE over the summer for a fleet of data buoys. For the datarates I need (4-10MB/hour transmit every 15-30 minutes) I think that LTE Cat1 makes the most sense for me from a cost and power standpoint. Cat4 is also an option, but seems like a hammer to kill an ant. What interests me is that the Cat1 chipset I'm considering is rated to 5Mb/s for UL while Cat4 is rated to 50Mb/s. The peak transmit power of cat4 over cat1 is just ~20% more.

If it takes 1/10th the time to transmit the same (fixed) payload at 20% more power, wouldn't this result in an 88% power savings per byte?

Assumptions in this statement are:
1) same TX power in dBm is required to get a given message out for a given location/time/weather condition.
2) The modem can be turned off between transmits - the dominant power draw is in xmit mode. I'm not aware of network restrictions requiring me to stay continuously connected in my region, but that would be an obstacle if any such restrictions existed.

The specific chipsets in questions are the ublox LARA-R2 and TOBY-L2 series.