I can give you first hand experience – I’ve been working full time as an engineer since 1995, and have been deployed (Army Reserve) three times, each time for a year or longer. I spent 2005 and half of 2006 deployed to Afghanistan.
The people I work with (I work for a Dutch–owned international chemical manufacturing company) have been incredibly supportive; they have thrown me going away parties each time I left, and have helped my family (wife and three kids) while I was gone – they even helped my wife move out of state while I was overseas (yes, I knew she was going).
The company has continued to pay the difference in my salary each time I was deployed because they support the Guard-Reserve. On top of that, the company continued medical insurance coverage for my family while I was deployed – at no cost to me. That is a significant amount of support.
On the flip side, I had four men under my command (four of 64 total, a Psychological Operations company) whose employers were completely unsupportive and vocally antagonistic about their employees being gone for a year. They each had their jobs when they returned, but in two of the cases, I had to contact the Judge Advocate General (military attorney’s office) to have them “chat” with the company’s management before the soldiers could have their civilian jobs back.
All that having been said, my absence creates an additional workload, obviously, and I have been exceptionally fortunate in that the site I work at can draw on additional support from our sister sites in the U.S. and Europe if needed. Not all companies can or will send an engineer from Germany or France to the U.S. for six months to cover the completion of a major capital project, or to complete a plant turnaround.
It’s never too late to make a commitment, unless you are too old, which is up to about 40 now, for military service. I’ve managed to be an engineer and a military officer for 21 years, and it’s a pain sometimes, but its been worth every sacrifice.