I have been doing a little bit of prep work for my upcoming Empire of the Petal Throne campaign. This has mostly consisted of re-familiarizing myself with the rules and setting (as presented in the boxed set, not the mountains of material that have come out since...) and assembling a vast collage of dungeon maps to use as my Jakalla underworld. I have also been re-reading the three Little Brown Books of OD&D, and I have been waffling back and forth between using mostly OD&D rules and classes or using the rules as presented in EPT.
Those of you familiar with EPT know that it is pretty close to OD&D anyway, with an interesting skill and magic system bolted on. My players will not be part of Tsolyani society, so I have no problem with them (as barbarians) playing the traditional OD&D classes instead of the EPT variants. Really, I have been wrestling with the desire to write my own magic system (or just use my TruE magic system, a sort of free-form casting system that I have been working on for a while now). This is especially true when it comes to Clerics, as I have always disliked divine magic as presented in D&D.
I have a newfound respect for the mechanical balance of OD&D after my readings of the last few days. I really like the way that the magic user is balanced against the fighter, especially compared with B/X D&D/Labyrinth Lord/AD&D. I particularly like that a first level magic user can have 6 (or more, with a high CON) HP, and that a fighting man is still a more effective combatant due to the easy availability of plate mail. In Labyrinth Lord, platemail costs a LOT of money. The average fighter probably couldn't afford platemail until at least 2d level in Labyrinth Lord (I will be comparing OD&D with Labyrinth Lord because I am playing in a Labyrinth Lord campaign). While this may be more historically accurate, I think the assumption in OD&D is that a fighting man is a professional fighter, and should have access to the tools of his trade. At 50 GP, platemail is within the reach of all but the poorest of fighters (3d6 x 10 starting GP in OD&D). This makes the 1st level OD&D fighter, with his d6+1 HP and AC of 2, quite a bit more durable than all but the most dexterous of his Labyrinth Lord equivalents. Likewise, the OD&D magic user is less likely to die from an errant scratch delivered by a mangy alley cat!
I will post more about my thoughts on the EPT ruleset and what I will do for a magic system soon.