kiwijunglist:
If you're gonna buy a Galaxy S1 there are about 10 different versions, they are all similar price so best to get "Galaxy S Plus i9001" version.
This has a different SoC than the normal Galaxy S i9000, a Qualcomm Snapdragon rather than a Samsung Hummingbird. The 1.4GHz Scorpion CPU in the GT-I9001 is indeed better than the 1.0GHz modified Cortex A8 in the GT-I9000. On the other hand the Adreno 205 GPU in the i9001 is a step backwards from the PowerVR SGX540 in the i9000. The amount of RAM may matter more than either of these things and is unchanged at 512MB.
This different hardware means that while the Galaxy S has a thriving hacker community and a wide variety of custom ROMs the Galaxy S Plus only has a few people asking if a way has been found to get root on it yet. The majority of people will never want root access or an alternative ROM, but some of us need features that aren't available as standard.
For me the faster CPU isn't enough to justify the slower GPU and higher cost of the Galaxy S Plus i9001 compared with the Galaxy S i9000. Both are good phones though so the other choice may be right for some people. If you want to change the software then the i9000 is clearly the better option.