If a portable and capable mitre saw fits for you then the Makita 40V should definitely be in your crosshairs. I've had mine almost a year now and it's proved to be extremely handy, plenty powerful, accurate and reliable.
My only gripe would be the dust port clogs up with no extraction. When you do stick an extractor on it, you have a moment wondering why you bothered and then the penny drops once again and you start digging out the port to clear the tubes.
A 2.5ah (effectively a 5ah 18V equivalent) battery has lasted me a day (sometimes 2) but then I'm not using it all day long. Compared to the 40V grinder (which you can measure runtime in blinks of an eye) I'd say it's pretty good on that front. BTW, the 40V charger is plenty quick... but has to be the noisiest charger of all time.