just fitted a ba caliper onto the terri rotor with no hassles, everything bolted up perfect and is running fine
is there any reason why i shouldnt leave it on, was a quick fix till i got a new one

The Territory front rotor is 322mm diameter, the caliper on your BA must have also been for that size rotor? cause the premium brake rotor on BA/BF is also 322mm dia. The standard BA rotor is 303mm dia. If that is the case then it is no worry at all.

no its a standard rotor on the ba

Obviously it is possible to get away with this, do the pads sit properly on the disc? Seems stange that there is a different caliper for the larger Disc but, if it works ok then great.