@Edgewise, nice, I think the best part of B/X-likes is that rules are simple enough to understand the implications of changes you might do. Do the same to, say, 4e, and the whole thing unravels.
Actually, here's a concept I came up with and haven't tested yet, but I kinda like:
- Single xp chart for all classes. (afaik Jim did this in the playtest doc)
- Saving throws as a combination of ability and class bonuses, as opposed to specific progression charts. (eg. "Fighter at the 5.th level has +4 class bonus to magic saves")
- HD limited at 4. (because fuck superhero pcs that's why, and that's still a shitload of HP)
- HD comes from Con, not class; You re-throw all HD at each level and take the larger HP. (Jim did this in the playtest doc, and I like it.)
- WFRP class abilities, no skills for non-specialists. Get a level in specialist if you want some... and...
- Multiclassing: at each character level (see xp chart) you decide which class to level.
- Saves come from class levels cumulatively: A 3. level fighter(1) - magic user(2) gets 1. level fighter + 2. level magic user save bonuses.