These saws have a 'cut-out' feature, which activates if pushed too hard, to protect the motor, etc. It is not quite the same as 'overloading' the motor, since it is protective and intentional.
I have had both saws (CS250 and CS300) cut-out when pressed in heavier, wet wood. But this is resolved by releasing and re-squeezing the trigger, and letting the saw do the work.
The chain is PowerSharp, with a built-in sharpening lever, so it just gets a touch-up whenever it feels like it is slowing down a bit.
I don't think so. They are on their 2nd generation string trimmer, and moving to their 3rd trimmer head, which uses an easy load, disc-type, line cartridge.
I have used them for trimming and edging - they work pretty well.
Since the batteries can be almost half the cost of some of these tools, it is helpful to look at them as a 'family' of OPE, unless you are certain that you will only be using one tool. Nice to be able to share/swap batteries among the different tools.
Philbert