Since both plans will have the same plan sponsor, each plan will have to consider in its coverage testing non-excludable employees (particularly employees who meet the eligibility and participation requirements for a benefit, but who are excluded based on classification). It doesn't make any difference from a testing standpoint whether there is one plan or two. It may make a difference if the one plan approach would require an audit, but each of the two plans will not. It also may make a difference if the employer does not want to communicate to all employees all of the benefit provisions that it want to provide to the different classifications of employees.
Keep in mind that coverage testing using the ratio test is done by type of contribution (elective deferrals, match, and non-elective employer contributions), and coverage testing using the average benefits tests is done based on benefits (assuming the plan passes a reasonable classification test or nondiscriminatory classification test). These additional testing steps can complicate the best of intentions.
Keep in mind the complexity of administration and of testing in any design. If the plan sponsor must be able to administer the plan or plans, or they could pay a steep price to correct operational errors. One of the most error prone situations is when employees change classifications during a plan year. This leads to some benefit accruals under each plan and the plan needs to have tight definitions for plan compensation and for eligibility service, vesting service and benefit accrual/allocation conditions.