yes the 733 is better becouse of faster bus and it is also not overclocked to much so it will not fail as fast as the 800, its a reason why acube stop selling these 800 you know..
I think they stop selling the 800Mhz not for any problem but because not all cpu modules are capable of running at 800Mhz, instead clocking to 733Mhz is safe for all and the speed is similiar.
I would add a Sam440ep 553Mhz with M9 is enough for most Amiga apps :-)