Much ado about nothing?
1. When you submit a plan to the IRS, in their words, they only "bless" (I use that term very loosely) the methodology that you are using to test, not the results. Resubmitting each year would be a waste of everyone's time and money. If the IRS were to audit, you would have to "reprove" that your method works anyway as this becomes an operations issue.
2. I would much prefer to have a full letter, knowing that at least you have some protection than trying to save a $1,000 bucks or so, when usually the owner saves far more than that in a cross-tested plan.
3. With regards to having 2 plans with exclusions, for small employer plans, the administrative costs will usually exceed the savings on the front end. Thus, it makes much more sense for small employers to use the class method to exclude.