Go to this website and zip through the links to find what the Euro's have been doing to their front axle housings. Some break the pinion snout, some break the actual 'dome' of the housing, others tend to shear off the area where the mounts bolt into.
http://www.k9rdj.co.uk/Going to something with a little more strength is what is being recommended here. The stock Vitara axle housing is steel in some models (IIRC 03's), and for the XL-7 model, I've only heard for the 5-sp's. The stock setup still requires a different passenger and driver cv shaft. Going the Anvil, you atleast get a matching set of driver's shafts to run.
I have a 02 XL-7 with the auto. I have the aluminum axle housing and the aluminum diff housing. In comparison, I really doubt you could get a stock Vitara steel housing for less than $300, and you wouldn't have the matching cv shafts. The option of the anvil is the best setup.
Think of it like a locker option: stock open, vs. limited slip, vs full time locker, vs. manual locker. Each has it's purpose, each has it's advantage, each has it's own cost.