I don't want to discount what others have said but a fast serial port is a hardware upgrade and will make using a modem more enjoyable, even on old phonelines. I use a GVP IO Extender and it makes a great difference from the standard amiga serial port. I think the Silversurfer uses a similar chip to the GVP and has buffering ability iirc, meaning it can store small bits of data while the processor offloads what it can when it can. Thus the cpu is not constantly tied down to the native serial port. This is not unlike the system upgrade afforded by scsi dma vs. polled ide. Of course, a 68060 can make even the old ECS chips run pretty nippy.
