Okay I think I see your point. Correct me if I'm wrong here - you're saying that you can have such a formula, but need to make sure you have proper backup showing proper plan operation in case of examination? I guess that is a valid design - however it seems to me to "push the envelope" a bit based on this wording from the memo:
“However, employer discretion that is not expressly stated in the plan document, and that leads to the manipulation of compensation, may result in operational disqualifying defects. If a Specialist reviewing a plan in the determination letter process has a concern about the employer’s ability to manipulate compensation for the benefit formula, the Specialist might consider a referral to Examination (subject to management approval).”
And also based on these comments from the ERISA Outline Book regarding the memo:
"Any employer that is considering amending its plan to utilize one of the types of formulas discussed in 6.b.2), 6.b.3) and 6.b.4) below, but without the explicit employer discretion language, should be aware of the potential examination pitfalls and be prepared to maintain records that will show proper plan operation. Practitioners designing these plans also should explore other ways to reach the contribution and benefit goals sought by the plan sponsor that are less likely to raise definitely determinable benefits concerns."
Anyway, thanks for the thoughts on this topic.