Descending Back to Basic

Before starting the previous campaign, I did a lot of playtesting by running one-shots for my friends before eventually settling on using Old-School Essentials with the optional rule for ascending AC. During this time I actually went through a couple of different systems, making minor tweaks as I went. The timeline went something like:

Swords & Wizardry -> B/X -> Basic Fantasy RPG -> Old-School Essentials

For the new campaign, my intent is to go back to B/X as our core system. The biggest change will be going back to descending armor class, which I haven't done since our earliest playtests. My players were 5e babies back then, and either didn't understand descending armor class, or thought it sucked. My reason for going back to it for the new campaign is twofold:

1. Virtually every player falls into one of two groups: either they get super into the rule set, learn how it works, and will completely understand and adapt to it; or they won't pay any attention at all, and just constantly ask me "how that works again" at every turn, no matter how easy I make it. For the former players, if I change to descending armor class, they'll quickly adapt to it and not have any issues. For the latter group, they'll always ask how it works, but they'd do that anyway, even if I made it as simple and modern as possible. So the reality is that it doesn't really matter which one I use, the same players are going to 'get it' and the same players are going to 'not get it'.
   
2. OSE does ascending armor in a really weird and frustrating way. Outside of OSE, the easiest way to convert back and forth between the two is to subtract one of them from 20 to find the other, since you are rolling a d20 to attack. It makes AC 3 becomes AC 17, it makes a +1 to hit stay a +1 to hit, and so on. This makes it so that an unmodified roll will hit the same ACs in both directions. For whatever Gygaxforsaken reason, OSE has AC 3 become AC 16. This seems like a minor, innocuous change at first, but it actually has some pretty frustrating ramifications. First of all, Normal Man now has a -1 to hit instead of just rolling a d20 straight. This feels weird and bad, because the entire to-hit matrices of D&D are so clearly and evidentially scaled to what a normal man can do. It's true that this means you don't have to give the level 1 players a +1 to hit (and that's possibly why OSE does it), but they'll still get a bonus at higher levels and they'll likely have a bonus or penalty to Strength/Dexterity even at level 1, so an extra +1 hardly makes a difference. Secondly, this makes monsters attack bonus really ugly and inelegant. Instead of monsters getting a +1 to hit for every hit die they have, they get... a +1 for every hit die beyond the first one. So instead of a 3HD monster getting a +3, they get a +2. This, more than anything, is the big deal breaker for me, because it makes converting modules a gigantic hassle when it really doesn't have to be.
   

That was quite a rant and I could keep going, but the bottom line is that OSE adds ascending armor class as an optional rule, but implements it so incredibly poorly that I can't in good faith recommend using it. It caused more than a few headaches when I was bouncing between modules from all sorts of different systems -- something that wasn't an issue running descending armor class, or even running BFRPG (Basic Fantasy only uses ascending armor class, but gets it right).

Seeing as we are back to descending armor class, I don't really see a great argument against using B/X. My personal 3-ring binder will have those Moldvay, Cook, and Marsh books in it, and I'm going to be telling my players that we're playing 1981 Basic/Expert Dungeons & Dragons. However, the OSE books are staying at the table for people to reference, because at the end of the day, there's not really any difference, and my players will only be using the rulebook to create new characters and level up. At least that's the idea, but that requires a nice little handout of house rules to really make it work. Fortunately, that's next on the agenda.