Redis cluster vs Redis Sentinel: when do you need a cluster?

we're currently running redis sentinel for our main caching layer and it handles about 50k ops/sec pretty comfortably. however, we're expecting a significant jump to around 200k ops/sec in the next quarter or two. the question is, at what point does it make sense to migrate to a full redis cluster? the main worry with cluster is all the added complexity of key routing and cross-slot operations, especially since our client libraries would need updates. is 200k ops/sec even achievable reliably on a single redis instance with proper hardware, or are we just delaying the inevitable cluster migration? keen to hear experiences on pushing sentinel setups to their limits and the triggers that made people switch.