T-Mobile 55+ plan: Is Upgrade Ready worth an extra $8/month?

I was previously on the Magenta 55+ plan for $70/month (2 lines), but T-Mobile automatically moved us to the more expensive Experience Signature w/ 55+ Savings plan for $92/month. I noticed that our current plan does not include the “Upgrade Ready” benefit. If I switch to Experience More w/ 55+ Savings 2.0 , it would be $100/month for our two lines, and it says: “Upgrade Ready every three years with the same great deals new T-Mobile customers get.” So basically, it would cost us an additional $8/month ($96/year, or $288 over three years) . For anyone who has this plan: Is the extra $8/month worth it for the Upgrade Ready benefit? How exactly does the 3-year upgrade period work? If I switch to Experience More w/ 55+ Savings 2.0 today, does the three-year clock start when I change plans, or do I have to purchase a new phone first? How soon after switching plans would I actually be eligible to take advantage of the Upgrade Ready benefit? Has anyone actually used this benefit? Did you get the same phone promotions that were available to new T-Mobile customers? We're not necessarily looking to upgrade (iPhones) immediately, but if the benefit is worthwhile, we're trying to decide whether it's worth paying the extra $8/month now.