Interval suitability is mixed: several tests closely match reference heart-rate data, while another misses fast changes. A chest strap remains sensible when precise interval intensity drives training decisions.
Pros: battery life, GPS accuracy
Cons: value for money, menu navigation
Responsive pace tracking and accessible buttons can work well during intervals. Very short repeats expose optical-sensor lag, and this generation does not promise a new sensor solution.
Pros: battery life, mapping and navigation
Cons: value for money, LTE connectivity