The way I have most commonly seen things done is to have the e-commerce platform handle the subscription if someone subscribes at checkout (and then sync to Klaviyo), and have Klaviyo handle the subscription if coming in from a Klaviyo signup form (then sync to the e-commerce platform). Then if someone requests to unsubscribe through either platform, that should be honored no matter where the request came from!

If integrated correctly, both platforms should be sharing the subscribe/unsubscribe data with each other! So it should be a pretty seamless process. 

Let me know if this makes sense, or if you have any questions!

Thanks, this is helpful.  In that case, I will focus on using the most appropriate tool for subscribe/ unsubscribe in a given flow rather than sweating on picking one or the other.