I suppose giving Expertise or lowering the DC end up having about the same result mathematically.
The problem, as in a design puzzle sort of problem, is that if you offer expertise, it needs to be completely free-range. A fighter or other martial needs to be able to choose any skill to apply expertise too, from history to perception and stealth. Meanwhile, if this "physical ability" system is designed assuming that the fighter has expertise, then it ends up being either ignored or the only choice.
Expertise in this fashion is free-range, as long as one understands backgrounds are meant to be
completely customizable!. The idea of "pay for a skill proficiency twice" gets you expertise, if you want something
not on your class skill list, you'll likely have to get it from your background.
So, while some players might take Athletics, or Brawn, or whatever for more "combat reasons", getting expertise in History or Medicine (field medic anyone?) or whatever is a viable option depending on your concept of course.
The thing is, doubling your lifting capacity or jumping distance is just not nearly as useful as stealth or perception, because using it effectively requires circumstances and clever play. Meanwhile everyone rolls stealth and perception checks consistently, even if they aren't built for them. I think even if you implement this system, you might still see a lot of people ignore it and put expertise into the more commonly useful skills. This is part of why I'm thinking of lowering the DCs. 15 isn't that much easier to hit if you are looking at normal ability score numbers, and the end result is till the high level PC hitting the number about 90% of the time (needing a 4 or better)
I get your point and it is worth considering. As for stealth and/or perception being overused, IMO that is another design flaw from WotC. It seems like this would have become appearant in the playtests. I'd have to work on the numbers to determine which method I'd prefer, but on the surface I'd be open to either.
Looking over the rest of it, I'm struck that doubling movement speed for a check is very extreme. IT essentially allows for a free dash action. I do want melee fighters to be faster, but this might be too much. The other uses in jumping or lifting will likely take actions or bonus actions (jumping is tricky) but the movement speed increase would be useless if it did. IT might be better to have the first movement increase be by 1.5 then 2 then 2.5 or 15/30/45. This makes the top speed 75 or 150 with dash, but that is with a base of 30 ft.
Sure, playtesting the ideas would reveal IMO if increases felt too much or insufficient. We have a "sprint" houserule which requires a check, and depending on the increase could require either a bonus action or your action. As a sprinter in college, you are pretty focused on moving quickly--so for that level of boost requiring your action seems appropriate.
I'm not against the more impressive top-speed, I'm more looking at the value of the dash action. It is already a very under-utilized action unless you can use it as a bonus action, and I'm worried that an easy doubling of movement speed would kill it entirely, except for those classes like the rogue or monk. Which, by the way, hit monumental speeds with even a bit of tweaking.
I guess that is part of the issue, as it is Dash is under-utilized other than Rogue, etc. Few times do characters rarely Dash except in chases, which aren't that common IME. I guess the important point is to have something in place if players want to use it.
Well, you do need to remember that the "max lift" is the "pick it up, maybe stumble 5 ft with it" score, not the lift and carry score, which is generally half of the max. So, halving to ~2850, and I can see a 20th level Goliath Bear Totem Barbarian with 24 strength being capable of carrying a small car down the street.
Oh, sure, I remembered! I was more focused on the max lift for combat reasons (lifting an Ogre and tossing it off a cliff or something...).
I've honestly debated on that. What holds me back is, again, the fantasy. Orcs and Goliaths will both have powerful build, and both are classically picked by people who want to be "the strong guy" and I want people to feel like that is a legitimate choice since useful cases of strength are pretty rare compared to other scores.
I think I would be much more inclined to leave Powerful Build as race specific, but if someone was playing a human and truly wanted that extra capacity, I'd find a way for them to achieve it.
Yeah, it's a tough call, I'll admit. But while Orcs and Goliaths (and Firbolgs!) have it by default, any other race has to spend a (rather steep IMO) cost of a feat! Considering most game run to 10th or so, most PCs will get 2 or 3 feats, 4 at the outside edge.
Hmm, I did forget about them getting advantage from a subclass ability. That might change the math a bit.
Well, advantage can also be accomplished through Help,
enchance ability, and other means, too. You often have to make a point of getting it, sometimes at a cost to another PC, but it isn't difficult to get IME.
Other than these "physical enhancements", what other concepts do you think would work well for a "plausible fantasy" but not "demigod gonzo" level?