Be careful if you are going to practice emergency avoiding action turns - you could overstress the airframe on your aged PA28 / C172 as well as inducing an unwanted upchuck from your passengers.
2close, well of course emergency turns should be taught by a flying instructor who knows the ins and outs of same - this means, amongst other things, that you must be below the max maneuvring speed and in the Utility Category (no rear pax permitted). So long as you take sensible precautions I would suggest that emergency avoiding turns can be safely practised in your average training a/c.
It goes without saying that if you had to do a REAL emergency avoiding action that momentary overstress is preferable to having a mid air collision.