The Garmin HRM-Pro heart rate monitor was released in 2020 and continues to serve as a very capable chest strap. If you bought one in 2020, you may have changed the battery out one or two times and experienced the inconvenience of the small screws on the battery access door. Battery compartment access is the only noticeable design change in the HRM-Pro Plus[1] with the one software improvement also available on the HRM-Pro.
While we often look for significant improvements in new products, there were no real faults in the HRM-Pro except for the terrible battery access design. Creating a new product that improves something and then serves as the default product for that category is perfectly acceptable and with the same price everyone should purchase the HRM-Pro Plus[2] now instead of the HRM-Pro. However, if you already have the HRM-Pro then there is no reason to upgrade to the new heart rate monitor until your existing model fails.
Also: The 5 best Garmin watch models: Which is right for you?[3]
In the early days of GPS watches, I wore a chest strap since heart rate monitoring from the wrist was not very accurate. After a while, chest straps bothered me and I found wrist-based monitoring to be good enough for my needs. With Garmin's heart rate monitors serving as the data source for running dynamics, and now with the 2022 Garmin watches, as the data source for running power I am back to working out with a chest strap. I am also now an active Hydrow user[4] so a chest strap is needed to get the most accurate workout experience.
The HRM-Pro (top) and HRM-Pro Plus (bottom) have different battery compartment access panels