@teltic Awesome! I hope you document your experience somewhere so that others can learn from your sabbatical.
If you can manufacture your layoff, then by all means do! Remember you can apply for unemployment benefits as well. At least three more months of about 60% pay! Not bad.
Re health insurance, Pretax 401K contributions come off the top of MAGI. Meaning that if you max out 401K (19K this year) your MAGI will only be 13K plus capital gains/dividends/interest in post tax accounts (realize this only applies to work sponsored accounts, not personal contributions to IRA). If you can manufacture your income to just over 15K (look up 125% poverty for exact $) you still get ACA over Medicaid. Run that through the marketplace and I think you could get a bronze plan VERY inexpensively, maybe even free. Since you will have made more last year they may ask for an explanation of why your income dropped, so be prepared to give it. Worst case, you just get the subsidies when you file taxes at end of year instead of monthly. But, from what I've read of others experiences, as long as you explain yourself when estimating income, it's usually not an issue. EDIT: Be sure your MAGI ends up above the Expanded medicaid threshold if you opt for this route, better to be a little over and lose a few bucks in subsidies than end up in the Medicaid rabbithole!
Investments... Well be sure you are OK with your investment plan. If you subscribe to the 80%+ US equity index investing, like so many on here, it could be a wild ride. This is part of the mental preparedness I discussed above. It's one thing to see a 20% drop when you are still saving most of your income, totally another when you can't add to holdings during the drop. So, no matter what, it'll be a good test run on how you feel about your investing.
I'm planning another sabbatical and likely switching careers for a third time. Probable execution is this summer/fall. For the short term I set up an 18 mo CD ladder with 1-year CD's for living expenses, as I have been preparing for awhile. Online banks are paying high 2's% right now on that product, so not bad. Each CD has 6 mos living expenses and they come to term 6 months apart. This way I can get a full year off without worrying and then 6 mos transition time to find my new gig, in case it takes awhile. These funds are in a separate bucket from my eventual FI funds, so it helps to put a hard cap on how much I will spend down.
Last time I took a sabbatical, it was out of pure frustration. personal problems, and unplanned. I was 31, I think. It also happened to be around 2009 in the heart of the great recession. Because I hadn't saved enough for it, I had to find some income to supplement savings. Even in the midst of double digit unemployment, I found a series of part time work that was stress free, enjoyable, flexible, albeit relatively low paying from what I was used to. One of them even lead to a second degree and my current career, which I enjoyed very much up until a year or so ago. The amount of personal progress from that period was remarkable, without it I would be a mess, if even alive right now. No regrets!!! EDIT: I can only imagine how well it will go when well planned and executed.