I also prefer VISA but I don't think there are more VISA functions than GPIB ones. The main advantages of VISA is portability and flexability. When you use the low level GPIB functions, you are restricted to using a GPIB controller from NI (not necessarily a bad thing) while with VISA, you can use a controller from any vendor that provides a VISA driver for their hardware. A VISA program is also simple to port to a serial/USB/Ethernet, etc. connection for the instrument.
I can't remember if I ever used the SendList but I think it would be a worthwhile experiment to replace it with two separate Send commands or two separate VISA Writes to see whether the instrument error goes away. You can do all of this debug work in MAX. There are interactive VISA and interactive GPIB options.
