Hi Ryvax
First, thank you for your service to Canada.
For the financial side, I am not much help. My only comment - why would you put money into a LIRA that does not have to be? Locked in is locked in - usually it is from a pension that you have money in but don't want to leave with the company. RRSPs and TFSAs have a lot more flexibility. A LIRA is no safer than anything else, it is just a place to hold investments, and they can be safe or risky.
For the rest - I am not going to be much help, this is such a personal choice. But this is probably where your decision really lies.
Random thoughts - Canada is a rather large country - so how far away is your posting from your home town? - i.e. is it easy to visit every so often, or just about impossible? And are you likely to move around, or is that a long-term posting?
Are you reasonably happy with what you are doing? Are you learning skills that will transfer to civilian life? For example, I had a student summer job once at CFB Kingston in the hospital lab, and I know any of the lab techs could have gotten a civilian job in an instant.
Your wife just got a one year job. Could she take it with her if you moved? Or is it location specific? And is she gaining valuable experience/skills with it?
Work hours - be realistic - if you had a civilian job that was similar (i.e. using your present skills) would it also be hours-intensive? Lots of people post here about their insane working hours, that is one reason they want to FIRE. And how easy would it be to find that job? And how likely is it that it would be closer to family?
Grandparents - and little children - they don't really remember people when they are little, so you have breathing room. Plus these days there is SKYPE (it keeps families on different continents in touch, so should work for you) and cheap long-distance phone and relatively cheap flights. Given the mobility of Canadians (my Dad said we were typical, relatives in 7 provinces, but only one family member where we were) lots of people do not live that close to family, and manage just fine. Is there more reason to be close to family? Would there be child care involved? There is no budget for child care right now.
And you know? You don't have to decide it rightthisinstant. This big a change in your lives should be considered very carefully. You have a window of 7 years - so you could leave now, in one year, 3 years, 5, whatever. And challenge your assumptions. Do you WANT to be that close to family? For one thing, if you are from a small town, the two of you have seen more of the world and you may find it hard to fit back in with people who have not been exposed to the new things that you have seen. Given your wife's new job, maybe hold off a year?
If you do decide to move, moving before the oldest starts school might be nice so he/she has a chance to make friends that will be in the same class.
Just a side note, that may or may not apply - lots of people get really gung-ho when they first discover MMM and the forums - if this is you, don't let it get to your head.
And we are a very opinionated bunch, but we have not had all the answers handed down to us from on high ;-)