Yeah, that's another advantage. Theoretically you can get down to <1 frame of input latency with an FPGA. I haven't found the latency on a software GBA emulator running on a computer to be noticeable, but some people might find this to be another advantage.
I think with a dedicated emulation handheld (non-FPGA), you could probably pull some tricks to bring down the latency though.
I think with a dedicated emulation handheld (non-FPGA), you could probably pull some tricks to bring down the latency though.