The worst thing would be getting your Nexus privileges revoked and be scrutinized every time you cross the US border, the inconvenience alone will make me not visit family and friends across.you won't get CD'd for gear/peptides in Canada but there was a user pretty recently who reported getting secondary searched on return to Canada due to HGH seizure (mailed) earlier in the year. Generally international personal quant is pretty low risk but if you have a security clearance or care about getting secondaried at the border it might be worth being mindful of that.
Nice to save cash but how much would you pay to get your name off of a list if all your mail starts getting opened and you have to talk to CBSA for an extra 30 minutes every time to fly in from out of the country