Thanks for replies. I am encouraged to go with powermeter for my current groupset.
I have an idea not to go with cs600, but try to find used or maybe new (i understand that they are discontinued) 725 power sensor for my 725x HRM i own. Thus i can keep my 725 and save $. Does this sound reasonable? Will 725 power be much worse than cs600? Are the precision of power data reading similar for both of them? What are main drawback of 725 power sensors? Is there anyone who have used both of them?