I don't have a whole lot of insight to the military to aviation transition, but have a bit of insight of the military IT to civilian IT. I had a friend who did networking in the military, and specialized in communications systems (requiring high amounts of mobility and security). He got out of the military and was very surprised to find that the skills he used in the military were barely relevant to the practices used in the civilian world. In his words, his military training was 10 years behind best practices in the civilian world, and he had a steep learning curve. For aviation, it may be similar from spending much of your career in a DC6 and then jumping into an A320. If you can, study some sample questions from the most recent version of the CCNA to confirm or deny if this is still the case, as you may be surprised.
I agree with others, you don't want to be in your 50's or 60's living with the regrets of taking the safer route, and realizing you no longer have the possibility of a long-term career in a field that may be your calling.