Quote Originally Posted by Sindeloke View Post
I've been playing around with the idea of "you can add one fixed integer and one die roll." So you can have flash of genius and bless on the same roll, but not bless and bardic inspiration, and not flash of genius and aura of protection. It's not as flexible as your "pick any two," but it'd very easy to track. Apart from preserving bounded accuracy, it would theoretically also encourage spreading buffs around.

You'd probably have to do something like 3.path did and give them explicit nonstacking types, though (static and rolled, or w/e). You don't want to be unclear about whether something like Archery Style counts as a fixed integer bonus, or whether shield stacks with a shield. (If things like Archery and shields did count, though, that would help to address certain other concerns you sometimes see on this board.)
Your solution is definitely the simpler, while maintaining most of what I was proposing anyway. I'm ok with Archery being counted as a fixed integer; not sure what other fixed bonuses you could stack with it outside of a magic weapon/ammunition, and personally I see those stacking with the Ability Modifier, not really their own thing anyway.
Shield becomes a bit more problematic (and one reason I'd rather it impose disadvantage than be a fixed amount). Since the question is whether it stacks with a mundane shield or not, you have two decent options (and one complicated one) - change it to disad, or have it grant +3 (if using a shield) or +5 if not - so you're never getting more than +5 outside of magical shields. (Which as with weapons, I'm perfectly ok with stacking.) You could even combine them, if you're ok with further complicating combat a bit. If the attacker doesn't have disadvantage, then shield grants disad. If the attack already has disadvantage, shield grants a +3 (or +5) bonus to AC (which will pretty much all but guarantee a miss.

I suppose a fourth option would be to let the shield caster pick which they'd prefer at the time of casting... though I'd definitely keep the +3/+5 version regardless.