Beacon makes a lot of changes to the basic d&d formulas while trying to stay pretty compatible with d20 materials (and to a large extent the AD&D and OD&D modules and supplements that preceded those). So although there is point based magic rather than Vancian magic, the spells and levels are pretty similar. There are Hit points and Armour Class and although Beacon hit points aren't points of damage - they are points to absorb hits - it is still essentially ablative damage. There are two phases in combat, but there is still an initiative each round. All the weirdness that comes from having a PC absorb sword strikes and lightning bolts still applies, thinly rationalized behind those trusty old mechanics.
I do sometimes wonder what would happen if I had decided to take Beacon off those rails however. In the beginning I tried to model a system where armor prevented damage and found it less then satisfying (you hit more but it was anti-climatic because - you were doing more rolls, more math and less damage and that was not exciting). I looked at using 2d10 or some other combination to normalize the dice rolls (more averages meant you succeeded more often at average things but less often at the exciting stuff that mattered). I thought of only using the stat bonuses and dropping the trusty old 3-18 since Beacon uses on the bonuses usually but again, that made a lot of stuff not work (like gloves +1 DEX) or made stat damage way too nasty. Most of the interesting changes I tried didn't really fit into the d20 framework and so I scrapped them.
But what kind of game would I go for if I wasn't worried about compatibility? What would I keep and what would I scrap if I was just going to build a game I thought was interesting and not one I cared about interfacing with the old modules and stuff? What kind of mechanics would lend themselves to the kind of game I like to run? More importantly what current mechanics would I drop because I was no longer worried about easy translation of all that sweet source material.
I would probably drop the 'd20 plus modifiers' thing and go with some other success mechanic. I like the idea of adding/removing dice instead of adding lots of modifiers. I might use an exploding dice mechanic but likely I wouldn't unless it needed to be added to increase excitement. I don't like wildly exploding dice, but something like L5R or V6 is OK. One of the things I really like about Beacon is that the stats are your basic 'presence' in the game but your skills are the way you deal with things. Your skills let you leverage or overcome your natural advantages. I'd keep the way the stats and skills work as much as I could. While figuring this out I'd probably change the range of success as well, make it a bit more focused. Your characters would start a bit more capable and they'd top out sooner too.
I guess the next biggest thing I would change is the combat system. There is something just off with d20 combat and I sure would like to wrestle with that. You want to keep it simple roll against a target and you don't want the damage to be so severe that combat becomes disincentivized however you do want to add some kind of effect of damage. It's not easy to mess with this - and a lot of people have tried. I do think I would want to keep hit points, but I would try to totally separate damage from the equation. I really like how FATE damage works in that you have consequences piling up if you blow out your buffer. I think I'd make the old hit point pool much smaller and have it replenish much more often. Starting with a base HP you'd get like one or two points per level. Weapons would only do a couple points, I might even remove the damage roll. I really like the simpler damage rolls in Beacon and might want to take that even further.
Anyway, you'd soak up the potential damage you take during a fight with your hit point pool but if you blew out your buffer you would start taking damage. After the fight your HP would come back really fast - like catching your breath - but the damage wouldn't. The damage would also have effects on your performance. That's not hugely different than how Beacon works now at low levels - damage cuts into your STR and that causes your bonuses to drop - but currently it's unwieldy and you have to calculate the changes all the time. I'd like something where you had like damage boxes and each one added -1 to all your rolls or something easy like that. Other effects too, I'd certainly keep the critical hit concept around.
As for stats - well I'd keep them but I would just have the bonuses, not the 3-18. Dino-Pirates of Ninja Island does this in it's d20 inspired system and I think it's a sensible direction to go. If you are not going to use the stats as a roll under substitute for skills then I don't see the need to keep track of them when all you want is the bonus. Just roll up the the -4 to +4 bonus or whatever and go with it - it would make spells and items that modify stats a lot more powerful too. I'd probably change this right now if it didn't really mess with all the d20 material.
I would totally go with your level equals the level of spell you can cast. Yes I would still keep levels because leveling up is awesome. I would cap it though because it's too hard to account for unlimited progression. I would probably only have like 6 or 7 levels or something, maybe an even 10. I'd reorganize the spells along those lines, and I'd keep the 'spells cost fatigue' kind of mechanic - just adjust it for the different kind of hit point system. Again I'd want to be dealing with 1 or 2 points instead of 7-8 points at a time for these mechanics.
Ah anyway I'm just woolgathering here. I still fully intend to keep Beacon on the d20 path and keep polishing it up until it's finished. If I did decide to play with these ideas, it would be a Beacon variant or some other game and I probably wouldn't throw it up anywhere. It's not like anyone needs yet another fantasy RPG right?