the only thing I have to go by on the gpu benchmark is that the guy in the video states that the Droid X performs about the same as the N1 in the GL Benchmark 2.0, which the Captivate blew it out of the water. I haven't seen a direct comparison myself between the two phones.
Linpack is raw computing power. On 2.1, I don't think you'll notice a significant difference between any of the 1Ghz phone. The difference is proven with 2.2 on the N1. Its linpack scores are 3-4x higher than all of the other 1gz phones on 2.1, due to JIT being enabled.