Just random thoughts..
I don't know how we got onto a discussion about HP but I don't see it as surprising because HP seems to be the big sticking point for a lot of people...
Anyhow as for the article.
What concerns me most is that these optional rules come bundled. Or rather that I am concerned HOW they become bundled. Let me explain.
I never had problems taking aspects of another system and introducing said aspects into my game. The problem arose when I had to do it for all aspects and modules going forward, and how to balance those extras with a core system.
I could give all creatures their con score at first level and 5 HP per level after that, but to do so I'd have to remember to add a variable amount of HP to every single monster I encountered later. Usually when I tried something like that it ended up less con score (instead of con mod) being replaced by 10 and dropping the 5 HP per level entirely, to be replaced by an extra 10 or 20 HP on top of everything.
That is kind of what I'm seeing here. Granted it will be easier to integrate the "grim and gritty" HP systems because those are one time functions than it will be to implement "facing" or "criticals", but when further modules come along without mentioning random rule 47 of subset K then it is going to get trickier and trickier. It is all too easy to forget a lot of tacked on rules, or remembering which were used in this campaign compared to another.
The other thing I worry about is how they are packaged. As we heard, other ways of doing HP will come in the "grim and gritty" module. But will the aspects of those modules be balanced throughout the longevity of the game?
We know they won't all have to be used to work, but will we have to buy other books that will have additional "grim and gritty" information in it to further flush out the criteria?
I know I'm interested in the variant HP recovery. I have heard a lot of talk, even from other people, wanting crit tables and long term wounds. But will each new supplement be (a) balanced with only aspects of this one module in mind and (b) on a certain level "force" us to continue buying this module to get the most up to date or most relevant info. The same goes for grid-based combat, facing, or anything else he talks about as modules coming down the tubes.
I don't want it to sound unappreciated because I love that they're rolling out new options. I just worry about how we'll be expected to introduce and integrate those things into our games.