QACA Safe Harbor Matching Contribution

A plan sponsor wants to change their traditional 401k plan to a safe harbor plan but are concerned about their contribution obligations should they suffer a down year or two in the future, so they are leaning towards a matching SH design.  I've heard that a safe harbor 'maybe' notice can only be used when the 3% SH nonelective contribution is being provided, whether the plan is a QACA or not.  One of their advisors, however, is insisting that you can use a 'maybe' notice for a SH QACA that provides matching contributions only, but this didn't sound right.  As I'm thinking it would be hard for participants to decide how much (or if) to defer if the employer can just rescind their offer for a match at any time during the year, I have to ask - am I correct to believe that the only type of SH plan (QACA or not) that can issue a 'maybe' notice is one that provides the 3% SHNEC?  Thanks in advance for any assistance.  

The maybe notice can only be issued for a Safe Harbor Non-elective. There is no "maybe we'll match safe harbor"

A Safe Harbor matching contribution can be discontinued mid-year by amending the plan to remove the match, providing 30 days advance notice of the discontinuation to the effected participants and making all matching contribution from BOY through the discontinuation in the notice. 

In either case a "maybe" SHNEC that is "no" or a discontinued mid year safe harbor match is not treated as a safe harbor plan for that year and is subject to ADP/ACP testing and does not get the "deemed not top-heavy" exemption if that is a concern.

If the advisor is insisting they are correct, have them provide a citation but you'll be waiting a longtime to receive one.