I was trying to find my post where I wrote more about this, but if you just read what the regs say, thre is nothing to prevent such an amendment. The regs don't say "anything in the notice is off limits." In fact the IRS has said you can amend to add hardships which should have been in the notice.
1.401(k)-3(e) - Plan Year Requirement
"1) General rule. Except as provided in this paragraph (e) or in paragraph (f) of this section, a plan will fail to satisfy the requirements of sections 401(k)(12), 401(k)(13), and this section unless plan provisions that satisfy the rules of this section are adopted before the first day of the plan year and remain in effect for an entire 12-month plan year. In addition, except as provided in paragraph (g) of this section, a plan which includes provisions that satisfy the rules of this section will not satisfy the requirements of § 1.401(k)-1(b) if it is amended to change such provisions for that plan year. "
In no way, shape or form does the profit sharing allocation method satisfy the rules of 401k12 or 401k13 or this regulation. It just doesn't. All of the controversy regarding this matter is NOT BASED ON A REASONABLE INTERPRETATION OF THE REGS. It is based on comments made by the IRS (yes, including their published notices, which however do not supersede the regs and do NOT say what is impermissible - only what is permissible ).
I'm so tired of this topic.