I looked at all the Dolphin models, including the m600 (which I really liked), but settled on the S300i. I really liked the specs of the M600 but I was pretty sure being wifi only there would be problems getting a decent enough signal out at the pool, even with a powerful router. We've had some issues with the power supply and I have to say Maytronics has been great to deal with. The app and the bluetooth is pretty much a joke (within 3' if you are lucky), although when it does work, the extra cleaning cycles using bluetooth are nice. The 300i (same as active 30i) does a great job in our pool. No problems with numerous submerged pine needles, fine dirt/dust and other things falling off the budding trees. Normally just need the quick 1 hour cycle and every couple days put it on the 2.5 hour cycle for a deeper cleaning.