What is the money actually being held in? Company stocks? Mutual funds, index funds? I agree with getting the free 4% for sure, but after that, it would depend on what exactly the company is offering, if that was something I was interested in having money invested in I'd do it, otherwise (and most likely) I'd just do my own thing with RSPs. Also, in some situations your extra money is better put into TFSAs.
I'm sure others will be more familiar with DCPPs. I haven't had that exactly myself. I did a brief search and it seems you may not get access to your money until retirement. Do you know what happens to your money if you leave the company and when exactly you can access it? If there's any lockdown, I'd put extra money into something else that I could more readily access whenever I wanted it - at semi or early retirement age, without any qualifications.