Dear Werb,
It is good you ask this question because the choice of practise piano is very important, the weight of the action is least important as the sound quality and variety of tone colour of the piano.
Tobias Matthay gives a great outline to choosing your piano in his book Act Of Touch, which is well worth reading before purchasing your piano.
To answer your question though, even though the heaviness of action is least important in my opinion, I am a perfectionist and like to tackle problems from many angles and I do own a Steinway which I had weighted to such a degree that my piano is the most difficult piano i play on.
And the results? Playing any other piano than my piano feels much easier, and my finger strength has been said to be great. However the problem is, you can get use to your piano and if you do not listen to the other pianos you play with absolute attention, your playing can be overly harsh, you must adjust to every piano, try the piano you will be reciting on before the concert.
Goodluck with choosing your piano.
From Matt.