MIDI Cable vs USB route? What is better?

I really dislike usb for anything beyond mice, keyboards and memory sticks.

I recently went up from an MT-4 to a Motu 128 express and it needs a dedicated usb port. Otherwise my outboard synths end up getting weird sysex, program changes and stray notes.

Not to mention the bus powered gear problems you can get into.

If you can find other options than usb, definately go with them, even if it costs a little more.

Of course on some instruments you don't have a choice as to whether or not to use MIDI or USB. Lots of new gear still only offers MIDI.

Having said that, there's no MIDI interface that I'm aware of that connects to a G5 that isn't USB-based, so now that this subject has come up, is there any advantage -- on a device that offers MIDI and USB -- to using one over the other?

Well, let's see... I'm using Unitor8 & AMT8 MIDI interfaces. There's a USB indicator LED on each, and it doesn't show any activity when I'm moving the mouse or typing; the LED's only show activity when the interfaces are receiving MIDI (when I play my controller keyboard). So this tells me that the interface's driver is filtering through only MIDI-related data.

On older Macs, the only option for MIDI interface connection to the computer were the serial and printer ports. These weren't designed specifically for use with music gear, just like USB isn't. Both USB and serial protocols are general purpose, serial data connections for use with any number of different peripheral devices. On older Macs the mouse and keyboard were connected to the ADB port, not the serial ports. So the difference between USB and serial port connections is that the serial port could be literally dedicated to a connection to your serial-based MIDI interface, mouse/keyboard data never entering that data stream; whereas with USB, your mouse, keyboard, and MIDI data co-mingle on the same data bus.

But USB transfers data at a much faster than the serial protocol (if I'm not mistaken), meaning that MIDI timing overall should be more accurate than it ever was in the serial days. Furthermore, it's likely the case that when you're playing on your controller keyboard that you're not mousing/typing at the same time. Therefore the intermingling of data intended for different destinations is probably not so great, meaning that the chances of your peripheral USB device's data (predominantly keyboard and mouse) affecting the timing of your MIDI data aren't so great.

So those are my stream-of-consciousness thoughts on the subject. It probably doesn't answer the OP's question, but I offer it as food for thought.

So what about PCI express USB expansion cards? That's probably the best approach on paper. Anyone have experience with these?