[kabdib]

If you find yourself doing a platform, you're going to run into these issues.

The biggest problem seems universal: You were an idiot and cut a corner three years ago, and you have to break something to move forward. Now what?

The Mac has some classic and poignant examples of this that have actually been trapping people for 50 years. Such as: Use of the high byte of a pointer to have non-pointer meaning (some 1980s ear Mac callbacks set flags in the "unused" high bits of a pointer, and the IBM 360 team made the same mistake in some of their OS data structures). In both cases, fixing this issue was pretty nasty.

Study history or repeat it, your choice. :-)