Jack, "loyalty" for me is a non-issue. Things either work the way I expect them to or they don't, and if they don't the company should fix it or I move on. You won't find me blindly supporting one brand name over another unless there is technical substance behind it.
As for business ethic, how do you define what is ethical from what is not? They set ranges of performance standards for their lenses and they have policies for dealing with what falls outside the range. My experience with Canon is that if you bring a lens to them you are not totally satisfied with - and I'm talking L lenses, not "walk-around" lenses - they will test it to see whether it falls within their range of acceptability. If it falls within the range, the dialogue with them is over-with. From their perspective nothing is unethical about this - they are simply following their own rules and telling you so. Take it or leave it.
Now, there are two problems with all this. (1) The customer doesn't matter. It is all driven by their own rules and policies. Some may call it corporate arrogance and disregard, others may call it rational corporate behaviour. Each to his/her own. (2) The "width" of their acceptable range for critical quality parameters may be broader than to the liking of you or me. I'm sure they know that. What they also know is that if they narrow the range the reject rate would be higher and the prices much higher. I have no doubt they can manufacture lenses consistently to meet the narrowest standards the industry has ever defined, but you can probably count on your fingers and toes the number of people prepared to pay the price. Think of it roughly this way - if the reject rate is one in ten, the other nine are priced to recover the costs of the one, so from a zero reject rate the price goes up about 11%. If the reject rate is one in three, the other two are priced to recover the one, so the price goes up 50%.
OK, beyond all that reasoning, I personally think Canon needs to pay more attention to their high end customers who are not CPS members and behave more flexibly, but they demonstrate over and over again that they don't. Fine, we know the situation and we play accordingly. For me it is straightforward: (1) Don't buy anything that has known issues which may trouble you, and (2) for everything else buy where the retailer will absorb the risk of returns and exchanges.
All that said, I'll still buy Canon cameras and lenses because on balance, what they offer still meets my needs best. Every one needs to come to their own determinations based on a balanced evaluation of what are their needs and expectations relative to what the various brands deliver - and I'd hazard a guess you won't find any within these price parameters that are systematically guaranteed to meet your every expectation - I don't have any studies to support that hypothesis, but it wouldn't stand to reason otherwise.
