You're being fooled by the marketing hype. You need to be expedition ready, no jacket is. And honestly, you're way over thinking it. That you even used the word "vest" tells me you don't have any experience with heated clothing. And fine, I see what you want, but that's not what you need. I too have military experience. And about 400k miles of riding experience, including over a decade of endurance motorcycle rallying experience, plus am a finisher in the IBR. When I finished that, more people had been in space then had finished the Iron Butt Rally. It's not extreme in the same sense as riding rural India, (been there), but you're riding 20 hour days, 11 days in a row, in all weather and on and off pavement on a daily basis. It's no cake walk.
If you want to layer instead of go with electric clothing, that's a personal choice. No harm, no foul. Potentially of more concern in realistic terms is not a gear failure, but if the bike you're riding can support the power draw. Eliminating that potential by choosing not to use it checks that off the 'what if' list. Look hard at merino wool.
I am planning ahead for riding through the Himalayas in India, on narrow single-lane road surfaces with very poor pavement, mud, large jagged rocks, loose sand, landslides, frigid mountain rivers, and semi-insane heavy truck drivers, over many days of continuous riding. The weather up in those mountains even in the summer is unpredictable, and can swing from temps in the 60s and 70s to below freezing due to both shifts in the atmosphere and from elevation over a period of hours or even minutes. Rain and snow are not uncommon at any time of year.
So, pretty much like anywhere else when you keep riding regardless of conditions.
Are you an idiot? I'm going to go out on a limb and say no, you're not. So you're going to use some common sense and caution in conditions that get a little hairy. Your speeds are going to be lower and you're going to pay attention. India sucks in high density city riding. It's nuts and get a loud horn, because that's how you tell other road users you are coming around. There is no lane usage, even buses and trucks go all over the entire road to navigate or pass. Down South, it's a little calmer, but you're going to be way far away from large cities for most of your riding.
In Peru conditions changed quickly, and what happened the last few days might bite you too, with washed out roads or high water coming out of the mountains still. I did a water crossing that had basketball size rocks jumping out of the water and the water was about 16" deep and very fast flowing. I has real concerns that if one of those fast moving rocks hit my wheel at the wrong time it would wash the bike out from under me and I'd go down, then quickly get sent down stream and over a 20' falls into boulders. What did I do? I waited for 4 hours until the rocks jumping thru the water were only baseball sized, then crossed it. Missed a train due to that and some road construction, but it was the safe thing to do. Frigging busses were being pushed from one side of the 'road' to the other in that water. It was fine by the time I crossed it, but still made you pay attention. I was riding a Honda falcon 400 enduro bike. Solid machine and you could get parts anywhere if need be. I wore the Darien on that trip, along with regular riding boots and the rest of the gear. I wish I'd had my ADV boots, but trying to pack and ship all your gear, (x2), in a seabag limits you. I did not ship a bike, just rented one there.
I get 'dressing for the crash'. I'm an ATGATT rider for a long time. I'm out on a ride today in Alabama, riding 150cc scooters on a 450 mile over night ride. Just poking along and having fun, back roads, gravel roads, some two lane highway and sure, some crazy drivers not paying attention too. I'm still wearing my Klim latitude jacket and armored pants, modular helmet, gloves and riding boots.
Spending a metric ton of cash on a jacket won't make you any safer. As far as more comfortable, a solid goretex jacket with good venting and modern armor that is comfortable to wear goes a long way. As I said before, you need to put various versions on and wear them for a while to compare them. Maybe a ride to Rigby, ID will help you since they have the entire line available in the showroom there and sell their stuff there too. (yes, I have been there) You don't need to be a Klim fanboi either, consider what works and how you use your gear. I hate their leg zippers on the pants. Too short. You have to take your boots off to get the pants off. That's a no bueno for me. I get to my camping place and I'm shucking gloves, helmet, jacket and pants, then getting busy with the tent ASAP. Sometimes in the rain or worse, so I'll leave the pants on. Sometimes in heat and after a hot day riding. To be able to shuck the pants too and move around in my LDComfort base layer with my boots on works very well for me. I don't want to have to pull a pannier off so I can sit down and more easily remove boots and get pants off before either putting on some other foot wear or putting my boots back on. Depending on how light you're packing and what set up you have, consider that reality. Consider what you're prioritizing when you stop for the day and what activities you'll be doing.
Don't be fooled that buying the most expensive gear available is somehow the same as buying the best gear for you. It's not. Maybe what works best for you will be the most expensive, but often that's not the case at all. Often you'll be packing more weight, less comfortable in a more restrictive jacket and living with limitations that you didn't think about before you just pulled the trigger on what looked so cool online and had great marketing hype.
I don't know your time line. But I strongly suggest what ever gear you take on your trip is gear you've been wearing for a while already and are used to.
