So, I'm moving through the spells sections, attempting to put together a solid working draft of the core rules to release as a play test version. It's coming together quite quickly, so I expect to have a draft to release in the next bit here (maybe next weekend?).
As I work through spells, I'm starting from the description in B/X as of 1981, checking the same spell against 1983, and then also checking it against how it was presented in 3.0... I can see how some decisions are shaped by the expected experience of players. Let's just look at healing...
In 3.0, the cleric has access to a healing spell at every spell level (1-4), increasing by +1d6 each spell level, and taking a bonus based on cleric level (capped depending on the level of the spell). This inflates to match character hp (which are quite a bit higher in 3.0 vs. B/X), so the totals are not that out of line... the difference is in availability of healing.
In B/X, you get cure light wounds as a level 1 spell (1d6+1 hp restored), and this is available as of level 2... your next pure healing spell is a level 4 spell (2d6+2 hp restored) that you don't get access to until you hit level 6 (1981, which has a VERY wonky spell progression for clerics) or until level 8 (1983). The ONLY benefit of cure serious wounds over cure light wounds is the fact that you can recover twice as many hp in the same action, assuming a fast-paced combat where every second counts. The problem here is that this spell is up against comparatively high utility spells (Animate Dead, Dispel Magic, Neutralize Poison, Prot. from Evil 10' radius) that simply give a LOT more bang for the buck. The options are to either move the spell down or increase its effectiveness. Right now, it is worth exactly two level 1 spells - and there's just no way that this is worth the trade off.
In the end, at least for play testing, I'm going to leave it at level 4 (which becomes available when you hit level 7 as a cleric), but give it an extra 1d6+1, moving it to a total of 3d6+3 hp restored. Now, it goes from restoring an average of 4.5 points to an average of 13.5... it's still not going to be a huge game changer, but it's more useful than it was.
I'm tempted to stagger even more, putting a healing spell at spell levels 1, 3 and 5... I mean, you can use a level 5 spell to bring a dead character back to life, yet with a level 5 spell you are struggling to restore 10 hp? Seems out of sync, for sure.
The other issue to consider is a default assumption of the game - that is, in B/X you will have fewer and fewer of your starting hp as you progress through the adventure. There is almost no expectation that you are meeting later threats at anywhere near full strength. 3.0 healing allows you to meet later encounters at near full hp, allowing you to delve deeper into the dungeon before you start to feel the burn. In B/X, a tough opening encounter can leave you with very little healing left and down some hps as you move on to area 2- and that's true even for characters in the level 4-6 range, if not later.