The answer was to consider wear.

As a general comment, derailleurs are designed for a certain cassette slope. So if you need a hanger extension to clear the low cog, you aren't changing the slant the derailleur works on, you're just lowering away from all the cogs. That's why the high gears (small cogs) can become harder to shift - you've moved the entire derailleur away from the small cogs. The only reason it works as all is due to the power of HG cogs.