The limitation is a huge TB number so you don't need to worry about that :-) . There are a hardware limitation though wich limits the size to 127Gb be it partition or whole harddrive (ATA133 HD's). If you would ever need a bigger (IDE) harddrive the powerflyer would be the solution.
The reason for why you need to have the boot-partition at a maximum of 2Gb is because the limitations are in the 3.1 ROMs wich needs to be patched by spatch. This means that you have to boot with kickstart 3.1 wich will only "take" 2Gb partitions, then it will patch the ROMs and are able to use larger partitions/harddrives.