I am no expert on bagpipes, but I've had my McCallums for almost four years now and I'm very happy with them. My understanding is that McCallum pipes themselves are the same regardless of the model (e.g. AB1's are the same as the AB4's but without the bling), so sound and performance-wise, you'd be getting the same as a more expensive set of McCallums.
Check out bobdunsireforums.com for more if you haven't already. All the best!