Both mediator ang Grex for the 1200 has advantages and disadvantages. Grex have the mecanical problem, mediator is more sturdy in this, but grex is faster and no memory swaping because of the local bus connector that is using (thanks to ppc implementation) but lack support. As far as 4000 both are sturdier and none of them has the penalty speed from swaping memory. My needs on classic hardware is running 3.9 if I want 4.0 I will go to to something like ACK or better A1. so my choice is Grex for 1200 and Mediator for 4000, and thats because both support V3 cards some decent but low end Sound card and a TV tuner card (not realy a "need"). On A1200 you can connect ethernet via pcmcia and the speed is OK for classic amiga needs.