In the comments to the post:
Does the B/X Fighter need to be Buffed? K-Slacker mentions how he doesn't like that at times the Cleric surpasses the Fighter in fighting ability. Now, I've never really examined this in detail before. I put the following tables in the comments section to that post but I wanted to pull them into a post of their own.
Table 1: Cleric vs Fighter THAC0
XP..…CLevel..….CTHAC0……Flevel……..FTHAC0
0………….1………………19………………1……………….19
1500……..2………………19………………1……………...19
3000……..3………………19………………2……………...19
6000……..4………………19………………3……………...19
12000…….5……………..17………………4……………...17
25000…….6……………..17………………5……………...17
50000…….7……………..17………………6……………...17
100000…..8……………..17………………7……………...14
200000…..9……………..14………………8……………...14
300000….10…………….14……………….9……………..14
400000….11…………….14……………..10……………..12
500000….12…………….14……………..11……………..12
600000….13…………….12……………..12……………..12
700000….14…………….12……………..12……………..12
Table 2: Cleric vs Fighter Average Hit Points
XP..…CLevel..….CAvgHP……Flevel……..FAvgHP
0………….1………………3.5…..………1……………….4.5
1500……..2………………7………………1………………4.5
3000……..3………………10.5……………2………….…9
6000……..4………………14………………3………………13.5
12000…….5……………..17.5……………4………………18
25000…….6……………..21………………5………………22.5
50000…….7……………..24.5……………6………………27
100000…..8……………..28………………7………………31.5
200000…..9……………..31.5……………8………………36
300000….10…………….35……………….9……………..40.5
400000….11…………….38.5…………..10……………..45
500000….12…………….42……………..11……………..49.5
600000….13…………….45.5…………..12……………..54
700000….14…………….49……………..12……………..54
So yes, from a hit point perspective the Cleric does intermittently surpass Fighters at low (from 1,500 to 12,000) experience point levels. However, I don't think the discrepancy is enough to tip the scales too far in the Clerics favour as the discrepancy only lasts for a short time.
Also, if the optional variable damage system is used, the damage output of the fighter will likely be higher as they will likely have a weapon that will do at least 1d8 damage and they might have a strength based damage bonus. Also fighters will likely have any magic swords that are found.