Found a possible solution to this. It is mentioned here...
https://lowpowerlab.com/forum/index.php?topic=1655.msg19923#msg19923I am all for solving it with a hardware/capacitor solution to lessen the learning curve here but personally, I don't think the large capacitors on the reset line is the best solution. Forcing a known SPI buss state during startup seemed to be a better one for at least me any ways. Resistors on all pins solved it only partially. I tried them both pull-up and pull-down and it will still get hung on rare occasion on several of the devices I have here. I have had zero issues when I resorted to forcing a logic low on all SPI pins together for the 10ms startup period of the RFM. Logic high works too but the RFM fails the buss state more reliably and does not hang while all pins are forced low at boot. At least this is what I observed over here while testing it. I have 2 different types of RFM69HW modules here. Some of these problems may possibly be board revision specific. Hsackaday's website even has some fixes for some with capacitors soldered incorrectly on some of the boards.
I can only take a guess and say that with the buss driven/forced low, it perhaps sees all pins low, fails the condition quickly, and continues to boot normally. After the initial 10ms wait, it is simply a matter of initializing it and every one I have here runs flawlessly after booting them that way. Others may have a different experience, and that is the nice thing about forums. I am sure that others will try this solution and give some feedback of their own on it.
I do however think that if flash is installed, a pullup should come installed with it, or at least a solder-bridge location to enable a pre-installed 10k resistor. -- Just an idea.
I think before anyone jumps to too many conclusions, like Felix was saying, before any hardware change is made, it should be tested through various sleep states and other wacky things at startup that a users might put one through. Personally, I don't use any kind of power savings, disable all over-current protection, and drive the PA to max snot on some of them with external antennas high in the air at the end of long coax cables. Haven't burned one up yet.