If you haven't bought one all ready, and don't have an Amiga, I'd recommend holding off until there are videos of it working well with floppy drives, hard disks, serial, sound, and erm... macs. The only stuff I've seen relating to one of these and similar devices, so far is a speed boos that could be achieved with a mild overclock, and came at the cost of only intermittent booting and multiple subsystems not working.
I really would love to see them working, but I'm not holding my breath until I hear someone like
@GeekDot is helping - a load of ROM patches will be required at the least.