So, There has been a lot of comparisons about 1E V 2e in another thread involving a game called San Fran, and I have definitely been involved in it.. and after trying to redesign characters, I've decided I'll get the ball rolling...
First and best change of 1E versus 2E, hands down? No debate. No question?
Flat XP costs
Players should not have to worry about always taking 5, 5, and 1 in a sheet or otherwise I'm wasting on a conservative estimate at least 30 experience points, with the possibility of up to let's say 50-70. The obvious response is, well don't tink your sheet out, and make a normal character, with a varied sheet and intentionally put yourself several dozen if not possibly up to a hundred xp behind someone that made a more focused sheet. All so I could pick up a single dot of computers that might come up once in the entirety of my roleplay. Or 2 dots in driving which will come up never. Or maybe that 1 dot in expression!
Worse still when you give players 400 xp to start and then tier and gate things thinking that characters like the ones I might design which are highly optomized, sit in the same category as a player who doesn't spend 2 weeks optimizing their shit. I'll throw 23 dice on an attack and they'll throw.. what? 14? 15?. I'll throw 14 on stealth and they'll throw 5, My larceny s 18 and they offer up a piddly perception of 7. In this very reasonable example the differences in power levels is basically such that my character would walk over any conflict that would be geared towards the other player, and their character would die quickly to anything more geared towards my own character level.
Just change your behavior a person might say, or perhaps there should be restrictions on what players can buy. No more than 1 attribute at a 1. So the solution is to create artificial house rules.. to try and prevent twinkery.. Except that litertally all that does is force the players who optomize to build to the letter of the rule as close as possible, and still end up with characters that are miles ahead d of the other players. If your going to make a house-rule like that, why not make one that instead of punishing Optimization freaks, makes them less worried about making mistakes n their sheets.. and makes it far easier for the less optimized to catch up. (Attribute caps exist for a reason after all) Even more important, it follows n the foot steps of the designers themselves decided was important for the game?
Flat XP removes this risk significantly. Yes, it is still possible to have wildly differing levels of competency as people go more broad than tall, but it's much easier to start broad and go tall in a flat system, versus a multiplicative then on.
TLDR: Going from 2e back to 1e is fucking hell, Multiplicative XP is terrible and forces every player to spend hours tinkering a sheet just to make a viable concept or litertally fall upwards of hundreds of xp behind another player.
Edit: This also says nothing about the fact that throwing 400 xp at a mage versus a giest, a giant panda and a werewolf will result in this gulf of power growing even further. The tier system idea is unfortunately flawed from the start in a cross platform game, and as the above hopefully demonstrates, even within self-contained splats.