LTPT top heavy and DB combo

So some advise eliminating a waiting period or making it very short for part-time deferral-only employees.  In the past if the plan was top-heavy they had to get 3%.  90% of our plans are top-heavy.  And I know SECURE 2.0 eliminates top-heavy for those otherwise excludable.  

So if a plan allows all participants entry into the plan say after 12-month wait and entry date, those with a Year of Service (1000 hours) will get a full employer contribution and those without will not - they can defer only. This will satisfy the LTPT requirement.  There is no testing on the deferral-only group, and no top-heavy required contribution.  This seems pretty easy except it's more enrollment for a plan sponsor.  I believe our clients generally will still want the 12-month waiting period.

Does this sound reasonable?

Also, if it is a DC/DB combo, are there any consequences?  I would think not.