I've added a couple of posts to this thread already, will add another here.
I've been shooting heavier draw weights for quite a few years now. Why? For a variety of reasons: I have a shorter draw length, am hunting bigger game animals than "just" deer (elk, moose, bear), the heavier draw weight bow provides the ability to shoot a heavier arrow at the same speed as a lighter arrow with the same trajectory, (or the ability to shoot a similar weight arrow at a higher speeds and thus a flatter trajectory, depending on how you prefer to phrase it) etc. Is this necessary for shooting deer within 20 yards? Likely not, but then again, my situation is different.
Over the years it's gotten a bit tiresome to have people say "you can't....." or "you shouldn't..."..... It works for me, so that's what I do; do what works for you. I've never quite understood the comments about going from 70 lbs to 80lb+ draw weight in a bow. ? Nobody really even comments about shoulder surgeries, blowing out your shoulder, drawing in cold weather when in stand when someone is using a 70 lb bow. So, that 10 lbs makes that much of a difference? (It's an odd phenomenon, mention 80 lb limbs and those cast of characters are brought up; not so with 70 lb limbs.)
It really kind of depends, doesn't it? Are you familiar with someone else's fitness routine, physical capabilities, etc.? Sure, sharing your experiences is a good discussion point on a forum, but it would also be helpful to know how long you were active, the types of proactive exercises you were doing, if any, wouldn't it? Everyone's physical abilities are different. For instance, would it be a good idea for an out-of-shape, non-exercising, couch-potato, or someone with previous shoulder issues to slap on 80 lb limbs and start yanking away? Nope. Would it be a good idea worth considering for a fit, active person that has strengthened his or her shoulders to work up to a heavier draw weight bow, whether that be 50lbs, 80lbs, or 100lbs, if they are performing shoulder-specific strength building exercises (pullups, standing or seated rows, one-arm rows) and shoulder/rotator cuff-specific, stabilizing exercises (internal and external shoulder rotations in several planes, among others), on a regular, year-round basis? Probably something they could consider. (Obviously, there are some limits - as we age, the number and size of muscle fibers decrease, this loss of muscle mass reduces strength, it takes muscles longer to respond, tendons become stiffer and less able to tolerate stress, connective tissue becomes more rigid and brittle, etc. It's a great ball of fun.)
The OP is a fit and active 39 year old that has already stated he is easily pulling back 70 lb bow. I'd say get the 70-80 lb limbs, set them at 70 lbs, and work your way up from there. If it gets too hard, back them down a bit. It it continues to be easy, crank them down to a higher draw weight. And be sure to do your proactive shoulder exercises, regardless of draw weight, physical fitness level, or age, before an injury occurs.