Line-breeding is generally the safest route to take. Inbreeding requires extremely extensive knowledge of all the individuals, and will show up any recessive problems but cannot introduce genetic faults that aren't already there. Outrcrossing is a complete gamble, and the resulting litter is likely to be very varied in quality, but at best average. Careful linebreeding is generally the most consistent in results.
sorry i mean inbreeding ops: not line breeding , although out cross isn't all bad my last litter has 2 doing very well in the ring , and of course line breeding is only as good as the line you have....good points Jeangenie