You can decide whether and how much to contribute each year, and how to allocate contributions among members. You can choose to make regular monthly contributions, or wait until after year-end, when the company's profits are known. In non-profit years you have the option of contributing from retained earnings. You can also discourage staff turnover by specifying that contributions don't vest with employees until after as much as two years of plan membership. There's no minimum contribution level, but contributions are subject to a maximum limit and do affect members' personal RRSP contribution limits.
Rules governing DPSPs are uniform across Canada.
Pension plans do involve more paperwork than Group RRSPs. For example, if your workforce is composed largely of reluctant savers, a mandatory plan does help them provide for their retirement. Also worth considering is the fact that, unlike most RRSPs, pension-plan assets are not available to satisfy the claims of the planholders' creditors. This type of plan specifies the amount the employer must contribute each year. Employer contributions are tax deductible.