I haven't used it, but I read up a little and found that subscribers and watch time from a promotion doesn't count toward monetzation anyway. In my niche, organic growth seems to be fairly slow, so even if I got good amount of traffic and subscribers from a promotion, it would be pretty worthless, since I doubt it would feed my normal content to new viewers once the promotion ended. Just doesn't seem like a good value at all to me.
Give us the subscribers and watch time that would be earned through the promotion, and maybe I would consider it. Do you spend a lot when you do those promotions? As far as YouTube making it harder, I would say yes. I mean, 1000 subscribers and 4000 watch hours is hard enough. Throw in the introduction of shorts, and it takes away from long form.