Implementing passes is just a change in the way you accept content in the Physical world. i.e. you are simply changing from from accepting a print out / paper coupon to a digital card. You can even give the customers a choice; and from data to date the majority of customer choose digital over plastic or paper format.
There are some considerations to account for. For example, a customer will be willing to hand over a printed coupon or email print out to a sales associate and happy for that paper to be kept, but a customer will not want to hand over their phone, other than showing the digital membership card / coupon in their phone. So staff will need to be able to scan the Pass, or write the number down from the phone. This is not technically difficult but there may be a change in process to your staff that will need to be communicated and reinforced. PassKit can supply best practice training materials if/as required.
You may also choose to implement additional layers of authentication (e.g. a photo of the customer on the membership card so your staff can also perform a facial recognition when a Pass is presented). Of course this is entirely optional.