The GF2 Go is faster but consumes significantly more power which eads to shorter battery life.
You decide which is more important to you.
Personally, I'd try to budget for the R7500 Mobility, as benchmarks have put it at over twice the speed of the GF2 Go in most cases and it still consumes slightly less power.
Either that or the GF4 Go, which seems to be benchmarking about 5% below the R7500 Mobility.